Marine aquarium
Encyclopedia
A marine aquarium is an aquarium
that keeps marine
plants and animals in a contained environment. Marine aquaria are further subdivided by hobbyists into fish only (FO), fish only with live rock
(FOWLR), and reef aquaria
. Fish only tanks often showcase large or aggressive marine fish species and generally rely on mechanical and chemical filtration. FOWLR and reef tanks use live rock
, a material composed of coral skeletons harboring beneficial nitrogen waste metabolizing bacteria, as a means of more natural biological filtration.
Marine fishkeeping is different from its freshwater
counterpart because of the fundamental differences in the constitution of saltwater and the resulting differences in the adaptation of its inhabitants. A stable marine aquarium requires more equipment than freshwater systems, and generally requires more stringent water quality monitoring. The inhabitants of a marine aquarium are often difficult to acquire and are usually more expensive than freshwater aquarium inhabitants. However, the inhabitants of saltwater aquariums are usually much more spectacular than freshwater aquarium fish.
kept anemones
outdoors, but these systems were very short lived. The first personal saltwater
fishkeeping began on a wider scale in the 1950s, starting with the basic rectangular glass aquariums (usually 20 gallon
), still popular today. Bleached coral
along with a substrate
of coarse crushed coral were the norm. Algae, including beneficial types such as coralline algae
, were viewed negatively and were generally removed. The clean, sterile tank was viewed as the healthiest.
The Aztec
Empire had 10 ponds of saltwater aquariums at Texcoco.
During the early days of marine aquaria, saltwater was collected at local beaches. Natural saltwater contains many unwanted organisms and pollutants. Aquarium literature of the time suggests that the most commonly kept marine fish were the percula clownfish
, sergeant major damselfish
, small, brackish-water
pufferfish
and scats
, jeweled blennies, and blue damsels
. Aquariums were equipped with large air compressor
s, and were heavily aerated
and filtered
(primarily with undergravel filters, a norm for some time).
An ever-growing number of hobbyists experiencing the inconvenience of gathering natural sea water and the concurrent development of analytical chemistry
techniques led to research into the chemical composition of sea water. Synthetic salt mixes were developed to replicate the chemical environment of the tropical ocean, including trace elements and salts. This advance made marine fishkeeping popular in areas without access to clean sea water.
Air driven, counter-current protein skimmer
s and reliable submersible electric heaters
were invented in Germany
. Various advances in filtration included trickle and hang-on filters, both allowing a more natural equilibrium in the aquarium environment. The advancement of fluorescent lighting technologies to provide higher output, along with metal halide
lighting, enabled the first reef tanks, making it possible to keep corals and other invertebrate
s without natural sunlight
.
More efficient chemical testing allowed aquarists to understand the chemical properties of aquariums. By the 1980s, a biologically-based understanding of how to maintain an artificial ocean environment brought more successful and widespread marine fishkeeping.
or acrylic, filtration equipment, lighting, and an aquarium heater. Marine aquariums can range in volume from less than 80 litres, (< 20 US gal) to over 1,200 litres (300 US gal). Small volumes are more difficult to maintain due to the more rapid changes in water chemistry. The majority of saltwater aquariums are between 160 and 400 litres (40 and 100 US gal).
24 to 28 °C (75.2 to 82.4 °F), these tanks include tropical reef tanks, as well as fish-only tanks. These tanks tend to have a low concentrations of microscopic plankton and other foods eaten by filter feeders. Most livestock for these aquariums are acquired through commercial means.
Since most coldwater cnidaria
are rare and coldwater corals only occur at great depths, hobbyists are largely confined to fish, crustacean
s and mollusks. Since there are very few commercially available coldwater fish, hobbyists usually have to physically acquire specimens. The most common way of doing this is by trolling or seining. Unlike commercially available tropical fish, whose behavior patterns and tank compatibilities are well documented, coldwater fish require much local ichthyology knowledge in order to maintain them.
Many temperate fish have specific local diet requirements, while others, like tautog (blackfish), will eat just about any crustacean or frozen foods. The blackfish should not be kept with crabs and mollusks, while other fish, like the oyster cracker toadfish, will do fine with any fish that is not small enough to fit into its mouth. Due to it being such a localized hobby, not many people go the route of local tanks. However, they are more cost-effective than reef tanks, cheaper and easier to maintain, and the fish hardier. It takes experience before one can successfully gage the compatibility of the fish in one's area.
, and is usually covered with beneficial algae, coralline and tiny invertebrates and bacteria that are desirable in the aquarium. Some examples of the microfauna commonly found on live rock are crab
s, snail
s, feather dusters, brittle star
s, starfish, limpet
s, abalone
s, and an occasional sea urchin
, sea anemone, coral, and sea sponge
. Also, if the aquarist is unlucky, a mantis shrimp
. Bristleworms are also common, most of which, while unattractive, are not harmful and are useful scavengers; some species can be pests, however. The addition of live rock is one of the best ways to ensure a healthy aquarium, as the rock provides a buffer to maintain high pH (8.0-8.3), alkalinity, and acid-neutralizing capacity. Alkalinity
is often known by a rather confusing term, "carbonate hardness
", or KH. This is usually measured in "degrees" (dKH) or meq/L.
The microfauna found on live rock are detrivores and herbivore
s (as they eat algae and fish waste), and provide fish with a natural, attractive shelter. Live rock usually arrives from online dealers as "uncured", and must be quarantined in a separate tank while undergoing the curing process, which involves the inevitable die-off of some of the rock's inhabitants and the subsequent production of undesirable ammonia
and nitrite
. Live rock that is already cured is available at most pet stores that cater to saltwater. Live sand
is similar to live rock and is equally desirable.
Sometimes hobbyists use so-called "dead rock", which is simply old live rock that has been allowed to dry out and to lose most of its live inhabitants, to keep unwanted pests out of their aquariums, and as an inexpensive alternative to live rock.
In general, marine aquariums have more complex filtration requirements than most freshwater aquarium
s. The various components frequently include wet and dry filters and protein skimmers. Protein skimmers are devices that remove organic compounds prior to their degradation, and are very useful in marine aquariums. Protein skimming is also used in the popular Berlin method
that relies on live rock and periodic partial water changes to degrade and remove waste products. The Berlin method requires large amounts of live rock in the aquarium. The rule of thumb
is 1/2–1 lb. per 1 US gallon (0.2–0.4 kg per 4 liters).
Some marine aquariums include a sump, which is an external container connected to the main aquarium with a water pump. In most setups, the sump is located below the aquarium and is fed water from the main tank via an overflow. An overflow at its simplest is a round hole drilled towards the top of the tank, connected via tubing to an output below it. As the water level increases past the height of the overflow, the water "overflows" the tank and falls through to the sump below. The water circulation is powered by a water pump in the sump, which pushes the water back into the tank, thus causing more water to flow over and perpetuating the cycle. There are many advantages to using a sump, both for the appearance and the health of the tank. The sump helps the appearance of the tank, because it allows filtration and maintenance equipment (protein skimmer, heater, activated carbon) to be kept out of sight of the main tank. It also ensures that the water level of the main aquarium never changes, as the overflow sets the water level in the main tank. The sump aids tank health by helping to oxygenate the water by increasing the amount of water/air surface area used for gas exchange.
Some marine aquariums also include a refugium
. Refugiums are small containers or aquariums that are hidden behind or beneath the main aquarium and connected to it via a water pump (often in a similar manner to a sump). Refugiums have recently become quite popular among reef aquarists because they can be used to serve several purposes such as adding water volume or providing a fish-free site for biological filtration in live rock and/or the sandbed. Fish-free refugiums host populations of copepod
s, amphipods, isopods, and other zooplankton
.
Regular cyclical lighting is used in aquariums to simulate day and night. This is beneficial for fish and invertebrates since it establishes a routine, enables them to rest, and makes them feel more secure. Aside from establishing a routine, high output lighting is required for many invertebrates such as corals and anemones to survive. Lighting in marine tanks that contain only fish and live rock is not an important issue. In aquariums containing invertebrates, however, where algal growth (of both free-living and symbiotic algae) is desired, more intense lighting is required. Various light sources include but are not limited to: natural sunlight, fluorescent, VHO fluorescent (Very High Output), T-5 fluorescent, compact fluorescent, LED
and metal halide. Each type of lighting has its own advantages and disadvantages. They all vary in initial cost, maintenance cost, spectrum obtainable, longevity, efficiency, and power.
because the intensity of sunlight is greatest there. Efficiently utilizing natural sunlight requires complex planning and, as such, this method is applied on only the largest reef
systems. Many times in the hobby natural sunlight is actually avoided due to the low spectrum of lighting it has. The yellow tint is often undesirable and can encourage bad algae growth.
s available which are more suited to aquariums than those of incandescent bulbs. They are also more efficient than incandescent lighting, averaging between 90 and 95 lumens per watt. The downside to regular fluorescent lights is that they do not have the intensity to penetrate into deeper aquariums.
VHO fluorescent lamps run at higher power levels, usually about three times the standard wattage for a given bulb length. They have the advantage of high light output, but the larger diameter bulbs limit the efficiency of reflectors and the number of bulbs that can be fit in an aquarium hood.
PC lighting is also high-power fluorescent lighting, but the tubes are thinner and are often folded over one another to reduce size. Most spiral shaped energy efficient light bulbs commercially available for house lighting are power compact fluorescent bulbs. PC bulbs are recommended to be replaced every six months to a year to keep the desired light spectrum.
T-5 HO lights are the newest variation on fluorescent lights. They are run at slightly higher power levels than standard fluorescent lamps, but are made significantly thinner than standard fluorescent bulb. This allows for more efficient reflector designs that get more light into the aquarium. Higher quality T-5 systems often match or exceed the output of equivalent power compact fluorescent or VHO lighting fixtures. On the downside, T-5 lighting is the most expensive type fluorescent lighting available. Many times it is much cheaper per watt, especially in the long run with the multiple T-5 bulbs being replaced, to go with an equivalent metal halide light setup over a T-5 setup if such high light output is requried.
All types of fluorescent lighting offer the same efficiency in lumens per watt; it is the shape of the bulb and reflectors that makes their overall outputs different.
Most metal halide fixtures are more expensive than fluorescent systems, but are required for some reef setups. Halide lamps concentrate heat as well as light output. The surface of an operating lamp becomes hot enough to cause second or third degree burns instantly, so this lighting technology must be used with caution. The heat produced can also warm the aquarium to unacceptable levels, possibly necessitating the use of a chiller for certain aquarium setups.
Reef-keeping enthusiasts have began to build their own LED light fixtures as well. Debate over their effectiveness towards coral is still inconclusive, particularly with respect to their ability to give off UV radiation, critical to obtaining a vibrant array of colors that most people interested in LED lighting are looking for.
LED lighting can be considered one of the most energy efficient and low impact options to lighting a reef tank as well, with a projected life expectancy of seven years.
s (albeit slightly unrepresentively) refers to the color of light being emitted by the lamp and is based on the concept of blackbody radiation. Light from the sun has a color temperature of approximately 5900 K and lighting systems with color temperatures >5000 K tend to be best for growing plants in both the marine and freshwater setting. 10,000 K light appears bluish-white and emphasizes coloration in fishes and corals. Higher up on the spectrum there are 14,000 K and 20,000 K bulbs that produce a deep blue tint which mimic the lighting conditions underseas, creating an optimal ambience for invertebrates and livestock present.
, Southeast Asia
, and the Red Sea
. Marine aquarium temperatures should mimic the natural environment of the inhabitants and are most commonly maintained at 23 to 28 degrees Celsius (73-82 °F). In regions where the ambient temperature is less than the desired temperature of the aquarium this generally necessitates the use of an aquarium heater. In some areas ambient temperature is greater than the desired temperature and refrigeration
devices, known as "chillers", are used to cool the aquarium water.
pH can be raised with a commercially available buffering agent
or through calcium-rich substrates. A calibrated calcium reactor
can assist in maintaining both pH and alkalinity. Using purified water from a reverse osmosis/deionization (RO/DI) unit can prevent KH and pH fluctuation.
The nitrogen
cycle refers to the conversion of toxic ammonia to nitrite and finally nitrate. While fish waste (urine and feces) and decaying matter release ammonia, the majority of ammonia released (approximately 60%) in both marine and freshwater aquariums is excreted directly into the water from the fishes' gills. Biological (bacterial) nitrification converts the ammonia into nitrite ions, NO2-, and then to nitrate ions, NO3-. Nitrate is readily taken up and assimilated by algae and hermatypic corals. Some nitrate is converted via an anaerobic bacterial process to free nitrogen, but this process is very difficult to maintain. In the recent past, most nitrate, which is less toxic to fishes and most invertebrates than nitrites, accumulated in the water until it was physically removed by a water change. However, many marine aquarists are now employing the use of a special section of the tank or separate tank altogether, called a "refugium." A refugium is, as its name suggests, a sheltered area that shares water with the primary, or display, tank. Refugiums usually contain a deep sand bed to allow anoxic zones to develop within them where anaerobic bacteria can convert nitrate into nitrogen gas, a useful means of nitrate removal. Various types of macroalgae can be grown and harvested from the refugium as another means of nitrate export. As refugiums become more common in marine aquaria, nitrate levels are easily manageable for even the novice hobbyist. Ammonia and nitrite should be tested regularly; any detectable levels (i.e., over 0 ppm) can be indicative of a problem. Nitrates should not exceed 2 ppm in reef tanks, or 20 ppm in fish-only tanks. It is sometimes acceptable to have a small amount of nitrate buildup, as some livestock, especially fish, are fairly tolerant of nitrate. Most corals, while able to assimilate nitrate, cannot be expected to survive, much less thrive, with high nitrate concentrations.
Other suggested tests include those for calcium
, carbonate
alkalinity, magnesium
, and other trace elements. It is often beneficial (and necessary) for the aquarist to research the water chemistry parameters for the specific organism that is desired.
. This process slowly introduces the organisms to the water composition of the new environment, preventing shock resulting from sudden changes in water chemistry. There are several different methods of doing this, including the use of a drip line, or of a measuring cup or other device to slowly mix water from the aquarium tank into a container with the new animal.
The drip line or trickle acclimating method is a safe and gentle way to introduce saltwater fish into a new home, and is a fairly simple one to perform. This procedure can be used to acclimate all types of marine as well as freshwater livestock. First, the fish is placed with all the bag water in a bucket or container of sufficient size for the fish to be reasonably covered with the water, and the bucket is then set on the floor next to the aquarium. Using some plastic air line tubing and an air gang valve, a siphon drip line is set up from the aquarium to the bucket. Tank water is allowed to drip slowly into the bucket, using the gang valve to adjust the drip rate, until the water dripped into the bucket equals about two to three times the original volume of the bag water. After testing the pH, salinity, and temperature of the water in the bucket to see if these parameters match that of the tank water, the fish is gently removed and placed into the tank.
maintenance. Larger (approximately 200 gallon) aquariums are much more stable and water changes may not need to take place if the nitrogen cycle
has fully established itself in the tank, although this is a controversial statement among aquarists. Water changes are used to maintain balance of calcium, carbonate alkalinity, and magnesium which are rapidly depleted in a reef aquarium, while also maintaining levels of other trace elements as well as removing toxic solutes which may accumulate from many different sources and are unable to be removed by even advanced filtration methods. Supplements are needed (such as calcium) when regular water changes alone are not able to maintain adequate levels, particularly those of calcium, carbonate, and magnesium. Water changes involve removing a fraction of the total volume of the aquarium, replacing that water with new pre-mixed saltwater. Pre-mixed saltwater has been dechlorinated and/or dechloraminated—typically with an additive such as bisulfite or through filtering. Water should be brought to the same temperature if more than a 5% change is occurring. Salinity should match that of the aquarium, or be dosed very slowly if altering the salinity. Aging and aerating saltwater (such as in a bucket with a powerhead
or airstone) is recommended as good practice to allow the pH to stabilize.
Replacement water should be of the same source as the aquarium, whether it be reverse osmosis
(RO), de-ionized (DI), distilled or from a municipal supply, in order to avoid drastic changes in water chemistry. In cases where one is replacing a tap water-based salt mix with a reverse osmosis-based salt mix, the replacement water should be added slowly over the course of several hours to avoid sending the aquarium inhabitants into osmotic shock
. However, large water changes are not advised under routine circumstances anyway, so this is really irrelevant. Municipal, or tap water, is not recommended for a marine aquarium as it often contains high levels of nitrates, phosphates, and silicates and other dissolved solids which fuel the growth of nuisance algaes, particularly diatoms, which appears as a rust colored powdery algae and grows in the overabundance of silicates present in all tap water. Water filtered by a four stage process including mechanical, carbon, reverse-osmosis, and de-ionizing components is recommended as this can provide the easiest route to absolutely pure water. Four and Five stage RO/DI filtration units can be obtained for as little as $100 and are a cost effective means of converting tap water into water usable in a marine aquarium.
are captive-bred on a commercial scale. Much collecting is done in Indonesia and the Philippines, where use of cyanide and other destructive collection methods, while discouraged, is unfortunately common. The majority of live rock is also harvested in the wild, and recent restrictions on this harvest in Florida have caused a shift to Fijian and aquacultured rock. Natural rock, because it is created by coral polyps, takes many years if not centuries to form, and is a vital habitat for countless marine species; thus, commercial-scale harvesting of naturally-occurring live rock has been criticized by conservationists. Additionally, many animal species sold to hobbyists have very specific dietary and habitat requirements that cannot be met by hobbyists (e.g. Labroides genus wrasses, the moorish idol
); these animals almost inevitably die quickly and have markedly reduced lifespans compared to wild specimens. Often these specific environmental requirements cause improperly housed lifestock's color and appearance to be poor. These issues are often downplayed by individuals and organizations with a financial interest in the trade. Hobbyists who support conservation should buy only certified net-caught fish (although ensuring the legitimacy of such claims can be difficult) or captive-raised fish, as well as farmed corals and to support legitimate reef conservation efforts. The majority of corals can be "fragged", whereby a portion of a larger captive coral is separated and can subsequently be raised into an individual specimen, allowing for coral propagation within the domestic aquarium; the trade in frags (i.e. fragments) offers a fantastic opportunity for marine aquarists to obtain new and unique corals while limiting the impact on the natural environment. Rare species and those without a history of being successfully kept in captivity should be avoided.
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
that keeps marine
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
plants and animals in a contained environment. Marine aquaria are further subdivided by hobbyists into fish only (FO), fish only with live rock
Live rock
Live rock is rock from the ocean that has been introduced into a saltwater aquarium. Along with live sand, it confers to the closed marine system multiple benefits desired by the saltwater aquarium hobbyist...
(FOWLR), and reef aquaria
Reef aquarium
A reef aquarium or reef tank is an marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the coral reef environment...
. Fish only tanks often showcase large or aggressive marine fish species and generally rely on mechanical and chemical filtration. FOWLR and reef tanks use live rock
Live rock
Live rock is rock from the ocean that has been introduced into a saltwater aquarium. Along with live sand, it confers to the closed marine system multiple benefits desired by the saltwater aquarium hobbyist...
, a material composed of coral skeletons harboring beneficial nitrogen waste metabolizing bacteria, as a means of more natural biological filtration.
Marine fishkeeping is different from its freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
counterpart because of the fundamental differences in the constitution of saltwater and the resulting differences in the adaptation of its inhabitants. A stable marine aquarium requires more equipment than freshwater systems, and generally requires more stringent water quality monitoring. The inhabitants of a marine aquarium are often difficult to acquire and are usually more expensive than freshwater aquarium inhabitants. However, the inhabitants of saltwater aquariums are usually much more spectacular than freshwater aquarium fish.
Marine fishkeeping history
The first saltwater tanks were Venetian glass jars where the RomansAncient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
kept anemones
Sea anemone
Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
outdoors, but these systems were very short lived. The first personal saltwater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
fishkeeping began on a wider scale in the 1950s, starting with the basic rectangular glass aquariums (usually 20 gallon
Gallon
The gallon is a measure of volume. Historically it has had many different definitions, but there are three definitions in current use: the imperial gallon which is used in the United Kingdom and semi-officially within Canada, the United States liquid gallon and the lesser used United States dry...
), still popular today. Bleached coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
along with a substrate
Substrate (aquarium)
The substrate of an aquarium refers to the material used on the tank bottom. It can affect water chemistry, filtration, and the well-being of the aquarium's inhabitants, and is also an important part of the aquarium's aesthetic appeal...
of coarse crushed coral were the norm. Algae, including beneficial types such as coralline algae
Coralline algae
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls...
, were viewed negatively and were generally removed. The clean, sterile tank was viewed as the healthiest.
The Aztec
Aztec
The Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...
Empire had 10 ponds of saltwater aquariums at Texcoco.
During the early days of marine aquaria, saltwater was collected at local beaches. Natural saltwater contains many unwanted organisms and pollutants. Aquarium literature of the time suggests that the most commonly kept marine fish were the percula clownfish
Percula Clownfish
The Orange Clownfish is widely known as a popular aquarium fish. Like other clownfish , it often lives in association with sea anemones. A...
, sergeant major damselfish
Sergeant Major (fish)
The Sergeant Major or píntano is a large, colourful damselfish. It earns its name from its brightly striped sides, which are reminiscent of the insignia of a military Sergeant Major...
, small, brackish-water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
pufferfish
Pufferfish
Tetraodontidae is a family of primarily marine and estuarine fish of the Tetraodontiformes order. The family includes many familiar species which are variously called pufferfish, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, toadies, honey toads, sugar toads, and sea squab...
and scats
Scatophagidae
The scats are a small family, Scatophagidae, of fishes in the order Perciformes.They are small fish native to the Indian and western Pacific Ocean that have been popular in the aquarium trade in the last 30 years...
, jeweled blennies, and blue damsels
Damselfish
Damselfish comprise the family Pomacentridae except those of the genera Amphiprion and Premnas. They can grow up to long. While most are marine, a few species inhabit the lower stretches of rivers in freshwater. Damselfish usually have bright colors. in tropical coral reefs, and many of those are...
. Aquariums were equipped with large air compressor
Air compressor
An air compressor is a device that converts power into kinetic energy by compressing and pressurizing air, which, on command, can be released in quick bursts...
s, and were heavily aerated
Aeration
Aeration is the process by which air is circulated through, mixed with or dissolved in a liquid or substance.-Aeration of liquids:-Methods:Aeration of liquids is achieved by:...
and filtered
Filter (aquarium)
Aquarium filters are critical components of both freshwater and marine aquaria. Aquarium filters remove physical and soluble chemical waste products from aquaria, simplifying maintenance...
(primarily with undergravel filters, a norm for some time).
An ever-growing number of hobbyists experiencing the inconvenience of gathering natural sea water and the concurrent development of analytical chemistry
Analytical chemistry
Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...
techniques led to research into the chemical composition of sea water. Synthetic salt mixes were developed to replicate the chemical environment of the tropical ocean, including trace elements and salts. This advance made marine fishkeeping popular in areas without access to clean sea water.
Air driven, counter-current protein skimmer
Protein skimmer
A protein skimmer or foam fractionator is a device used mostly in saltwater aquaria to remove organic compounds from the water before they break down into nitrogenous waste...
s and reliable submersible electric heaters
Heater (aquarium)
An aquarium heater is a device used in the fishkeeping hobby to warm the temperature of water in aquariums. Most tropical freshwater and marine aquariums are maintained at temperatures that range from 22-30 °C . The types include glass immersion heaters and undergravel heating...
were invented in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. Various advances in filtration included trickle and hang-on filters, both allowing a more natural equilibrium in the aquarium environment. The advancement of fluorescent lighting technologies to provide higher output, along with metal halide
Metal halide lamp
Metal-halide lamps, a member of the high-intensity discharge family of lamps, produce high light output for their size, making them a compact, powerful, and efficient light source. By adding rare earth metal salts to the mercury vapor lamp, improved luminous efficacy and light color is obtained...
lighting, enabled the first reef tanks, making it possible to keep corals and other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s without natural sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
.
More efficient chemical testing allowed aquarists to understand the chemical properties of aquariums. By the 1980s, a biologically-based understanding of how to maintain an artificial ocean environment brought more successful and widespread marine fishkeeping.
Marine aquarium components
The major components are an aquarium, usually made from glassGlass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
or acrylic, filtration equipment, lighting, and an aquarium heater. Marine aquariums can range in volume from less than 80 litres, (< 20 US gal) to over 1,200 litres (300 US gal). Small volumes are more difficult to maintain due to the more rapid changes in water chemistry. The majority of saltwater aquariums are between 160 and 400 litres (40 and 100 US gal).
Types of marine aquariums
Marine aquarists typically divide saltwater aquariums into those housing fish only, those housing fish with live rock, and those primarily designed to house corals and other invertebrates (also known as reef aquariums). Many fish hobbyists also divide the types of saltwater tanks based on the water temperatures at which they are kept.Tropical marine
The most common type of saltwater fish tank, the tropical marine tank, houses marine animals from tropical climates. Usually kept between24 to 28 °C (75.2 to 82.4 °F), these tanks include tropical reef tanks, as well as fish-only tanks. These tanks tend to have a low concentrations of microscopic plankton and other foods eaten by filter feeders. Most livestock for these aquariums are acquired through commercial means.
Temperate marine (coldwater marine)
One of the more obscure types of fish tanks, the coldwater marine tank, holds fish of temperate climates, with temperatures ranging around 10 to 24 degrees Celsius (50–75 °F). While most of these tanks are not as aesthetically pleasing as their tropical counterparts, colorful species such as dahlia anemones and the ornate cowfish can be found. However most coldwater fish are gray or dull in color. Most colorful species are found in the western pacific and west coast of North America. These tanks also tend to require extra skill to maintain.Since most coldwater cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...
are rare and coldwater corals only occur at great depths, hobbyists are largely confined to fish, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and mollusks. Since there are very few commercially available coldwater fish, hobbyists usually have to physically acquire specimens. The most common way of doing this is by trolling or seining. Unlike commercially available tropical fish, whose behavior patterns and tank compatibilities are well documented, coldwater fish require much local ichthyology knowledge in order to maintain them.
Many temperate fish have specific local diet requirements, while others, like tautog (blackfish), will eat just about any crustacean or frozen foods. The blackfish should not be kept with crabs and mollusks, while other fish, like the oyster cracker toadfish, will do fine with any fish that is not small enough to fit into its mouth. Due to it being such a localized hobby, not many people go the route of local tanks. However, they are more cost-effective than reef tanks, cheaper and easier to maintain, and the fish hardier. It takes experience before one can successfully gage the compatibility of the fish in one's area.
Live rock
Live rock is rock that has been in the ocean, composed of limestone and decomposing coral skeleton, usually around a coral reef such as those around FijiFiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
, and is usually covered with beneficial algae, coralline and tiny invertebrates and bacteria that are desirable in the aquarium. Some examples of the microfauna commonly found on live rock are crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s, feather dusters, brittle star
Brittle star
Brittle stars or ophiuroids are echinoderms in the class Ophiuroidea closely related to starfish. They crawl across the seafloor using their flexible arms for locomotion. The ophiuroids generally have five long slender, whip-like arms which may reach up to in length on the largest specimens...
s, starfish, limpet
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...
s, abalone
Abalone
Abalone , from aulón, are small to very large-sized edible sea snails, marine gastropod molluscs in the family Haliotidae and the genus Haliotis...
s, and an occasional sea urchin
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
, sea anemone, coral, and sea sponge
Sea sponge
Sponges are animals of the phylum Porifera . Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells. While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells, but can also have...
. Also, if the aquarist is unlucky, a mantis shrimp
Mantis shrimp
Mantis shrimp or stomatopods are marine crustaceans, the members of the order Stomatopoda. They are neither shrimp nor mantids, but receive their name purely from the physical resemblance to both the terrestrial praying mantis and the shrimp. They may reach in length, although exceptional cases of...
. Bristleworms are also common, most of which, while unattractive, are not harmful and are useful scavengers; some species can be pests, however. The addition of live rock is one of the best ways to ensure a healthy aquarium, as the rock provides a buffer to maintain high pH (8.0-8.3), alkalinity, and acid-neutralizing capacity. Alkalinity
Alkalinity
Alkalinity or AT measures the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate. The alkalinity is equal to the stoichiometric sum of the bases in solution...
is often known by a rather confusing term, "carbonate hardness
Carbonate hardness
Carbonate hardness, or carbonate alkalinity is a measure of the alkalinity of water caused by the presence of carbonate and bicarbonate anions. It is usually expressed either as parts per million , or in degrees KH...
", or KH. This is usually measured in "degrees" (dKH) or meq/L.
The microfauna found on live rock are detrivores and herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s (as they eat algae and fish waste), and provide fish with a natural, attractive shelter. Live rock usually arrives from online dealers as "uncured", and must be quarantined in a separate tank while undergoing the curing process, which involves the inevitable die-off of some of the rock's inhabitants and the subsequent production of undesirable ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
and nitrite
Nitrite
The nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...
. Live rock that is already cured is available at most pet stores that cater to saltwater. Live sand
Live sand
Live sand, a term used in aquarism, is natural reef coral sand populated with millions of beneficial bacteria and organisms which aid in the dissolving of organic wastes like ammonia, nitrites and nitrates produced by larger organisms in saltwater aquariums...
is similar to live rock and is equally desirable.
Sometimes hobbyists use so-called "dead rock", which is simply old live rock that has been allowed to dry out and to lose most of its live inhabitants, to keep unwanted pests out of their aquariums, and as an inexpensive alternative to live rock.
Filtration
In general, marine aquariums have more complex filtration requirements than most freshwater aquarium
Freshwater aquarium
A freshwater aquarium is a receptacle that holds one or more freshwater aquatic organisms for decorative, pet-keeping, or research purposes. Modern aquariums are most often made from transparent glass or acrylic glass. Typical inhabitants include fish, plants, amphibians, and invertebrates, such as...
s. The various components frequently include wet and dry filters and protein skimmers. Protein skimmers are devices that remove organic compounds prior to their degradation, and are very useful in marine aquariums. Protein skimming is also used in the popular Berlin method
Berlin Method
The Berlin Method of biological filtration is a method for maintaining a clean and stable environment within a saltwater aquarium, typically a coral reef system. This method relies on the use of ample live rock...
that relies on live rock and periodic partial water changes to degrade and remove waste products. The Berlin method requires large amounts of live rock in the aquarium. The rule of thumb
Rule of thumb
A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...
is 1/2–1 lb. per 1 US gallon (0.2–0.4 kg per 4 liters).
Some marine aquariums include a sump, which is an external container connected to the main aquarium with a water pump. In most setups, the sump is located below the aquarium and is fed water from the main tank via an overflow. An overflow at its simplest is a round hole drilled towards the top of the tank, connected via tubing to an output below it. As the water level increases past the height of the overflow, the water "overflows" the tank and falls through to the sump below. The water circulation is powered by a water pump in the sump, which pushes the water back into the tank, thus causing more water to flow over and perpetuating the cycle. There are many advantages to using a sump, both for the appearance and the health of the tank. The sump helps the appearance of the tank, because it allows filtration and maintenance equipment (protein skimmer, heater, activated carbon) to be kept out of sight of the main tank. It also ensures that the water level of the main aquarium never changes, as the overflow sets the water level in the main tank. The sump aids tank health by helping to oxygenate the water by increasing the amount of water/air surface area used for gas exchange.
Some marine aquariums also include a refugium
Refugium
Refugium may refer to:* Refugium , an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply...
. Refugiums are small containers or aquariums that are hidden behind or beneath the main aquarium and connected to it via a water pump (often in a similar manner to a sump). Refugiums have recently become quite popular among reef aquarists because they can be used to serve several purposes such as adding water volume or providing a fish-free site for biological filtration in live rock and/or the sandbed. Fish-free refugiums host populations of copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s, amphipods, isopods, and other zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
.
Lighting
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
and metal halide. Each type of lighting has its own advantages and disadvantages. They all vary in initial cost, maintenance cost, spectrum obtainable, longevity, efficiency, and power.
Natural sunlight
The most primitive lighting source is natural sunlight. This is only effective in areas near the equatorEquator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
because the intensity of sunlight is greatest there. Efficiently utilizing natural sunlight requires complex planning and, as such, this method is applied on only the largest reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
systems. Many times in the hobby natural sunlight is actually avoided due to the low spectrum of lighting it has. The yellow tint is often undesirable and can encourage bad algae growth.
Incandescent
Incandescent lamps have been phased out over the years. They are wasteful of energy, producing between 15 and 30 lumens per watt of power (out of a possible 683 lumens per watt for an ideal light source). They can be found many times in older aquarium light hoods. They burn out frequently, put off a lot of heat, and normally do not have an appropriate spectrum associated with them. Most incandescent lamps can be replaced with commonly available and efficient screw in power compact bulbs.Standard fluorescent
Standard fluorescent tubes are the common light bars you find in commercial ceilings. Fluorescent lighting has more color temperatureColor temperature
Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of...
s available which are more suited to aquariums than those of incandescent bulbs. They are also more efficient than incandescent lighting, averaging between 90 and 95 lumens per watt. The downside to regular fluorescent lights is that they do not have the intensity to penetrate into deeper aquariums.
Higher output fluorescent
There are several improved variations of fluorescent technology. The main ones are very high output (VHO), power compact fluorescent (PC), and T-5 high output (HO).VHO fluorescent lamps run at higher power levels, usually about three times the standard wattage for a given bulb length. They have the advantage of high light output, but the larger diameter bulbs limit the efficiency of reflectors and the number of bulbs that can be fit in an aquarium hood.
PC lighting is also high-power fluorescent lighting, but the tubes are thinner and are often folded over one another to reduce size. Most spiral shaped energy efficient light bulbs commercially available for house lighting are power compact fluorescent bulbs. PC bulbs are recommended to be replaced every six months to a year to keep the desired light spectrum.
T-5 HO lights are the newest variation on fluorescent lights. They are run at slightly higher power levels than standard fluorescent lamps, but are made significantly thinner than standard fluorescent bulb. This allows for more efficient reflector designs that get more light into the aquarium. Higher quality T-5 systems often match or exceed the output of equivalent power compact fluorescent or VHO lighting fixtures. On the downside, T-5 lighting is the most expensive type fluorescent lighting available. Many times it is much cheaper per watt, especially in the long run with the multiple T-5 bulbs being replaced, to go with an equivalent metal halide light setup over a T-5 setup if such high light output is requried.
All types of fluorescent lighting offer the same efficiency in lumens per watt; it is the shape of the bulb and reflectors that makes their overall outputs different.
Metal halide
Metal halide lights are generally the highest output lighting commercially available. They produce about 90-100 lumens per watt of power. This is roughly the same as fluorescent. The improvement with metal halides is that they concentrate this light output into a very small space, whereas fluorescent lights evenly illuminate the entire aquarium. This is often referred to as point source lighting, and is what causes the rippling visual effect on many advanced aquarium setups. This concentration of light output increases the intensity, allowing metal halide lamps to penetrate light to even the very bottom levels of most aquariums. Metal halides are available in many color temperatures, from 6500 K up to 20,000 K, though bulbs as high as 50,000 K are occasionally found. The downsides of metal halide lighting are the initial cost and the heat produced.Most metal halide fixtures are more expensive than fluorescent systems, but are required for some reef setups. Halide lamps concentrate heat as well as light output. The surface of an operating lamp becomes hot enough to cause second or third degree burns instantly, so this lighting technology must be used with caution. The heat produced can also warm the aquarium to unacceptable levels, possibly necessitating the use of a chiller for certain aquarium setups.
LED
The most recent addition to the list of aquarium lighting technologies is LED lighting. These have the potential to be much more efficient than any other technology, but are not fully developed. LEDs have the advantage of point source lighting, but are also adjustable to most power levels. This allows for more advanced lighting schedules, the simulation of cloud cover, or even lightning storms. So far, LEDs have found use mainly as lunar lighting in commercial products.Reef-keeping enthusiasts have began to build their own LED light fixtures as well. Debate over their effectiveness towards coral is still inconclusive, particularly with respect to their ability to give off UV radiation, critical to obtaining a vibrant array of colors that most people interested in LED lighting are looking for.
LED lighting can be considered one of the most energy efficient and low impact options to lighting a reef tank as well, with a projected life expectancy of seven years.
Overall lighting considerations
When considering lighting for an aquarium, there are generally two factors to consider: wattage and color temperature. Depending on the type of lighting (i.e. fluorescents, metal halide, etc.) the wattage of light emitted may vary considerably, from tens of watts to several hundred watts in a lighting system. Wattage, while not indicative of color, is equivalent to power and essentially determines how brightly the light will shine. Due to the scattering of light in water, the deeper one's tank is, the more powerful the lighting required. Color temperature, measured in kelvinKelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
s (albeit slightly unrepresentively) refers to the color of light being emitted by the lamp and is based on the concept of blackbody radiation. Light from the sun has a color temperature of approximately 5900 K and lighting systems with color temperatures >5000 K tend to be best for growing plants in both the marine and freshwater setting. 10,000 K light appears bluish-white and emphasizes coloration in fishes and corals. Higher up on the spectrum there are 14,000 K and 20,000 K bulbs that produce a deep blue tint which mimic the lighting conditions underseas, creating an optimal ambience for invertebrates and livestock present.
Heating
Most marine aquarium inhabitants are endemic to tropical reefs and waters in AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Southeast Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
. Marine aquarium temperatures should mimic the natural environment of the inhabitants and are most commonly maintained at 23 to 28 degrees Celsius (73-82 °F). In regions where the ambient temperature is less than the desired temperature of the aquarium this generally necessitates the use of an aquarium heater. In some areas ambient temperature is greater than the desired temperature and refrigeration
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...
devices, known as "chillers", are used to cool the aquarium water.
Water testing
Marine aquarists commonly test the water in the aquarium for a variety of chemical indicators of water quality. These include:- Specific gravitySpecific gravitySpecific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
, a relative measure of water density, is normally maintained between 1.020 and 1.024 in aquariums with fish only, and 1.023 and 1.026 for aquariums containing invertebrates. - SalinitySalinitySalinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
should therefore be between 28 and 35 ppt, with the higher values being beneficial in advanced reef systems. Because salinity is by definition directly related to specific gravity, both can be tested with an inexpensive hydrometerHydrometerA hydrometer is an instrument used to measure the specific gravity of liquids; that is, the ratio of the density of the liquid to the density of water....
or refractometerRefractometerA refractometer is a laboratory or field device for the measurement of an index of refraction . The index of refraction is calculated from Snell's law and can be calculated from the composition of the material using the Gladstone-Dale relation....
. - pHPHIn chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
should be maintained between 8.1 and 8.3. - Ammonia should be near zero.
- NitriteNitriteThe nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...
should be near zero. - NitrateNitrateThe nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
should be well below 10 ppm, but close to zero is best. - PhosphatePhosphateA phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
should be below 0.3 ppm. - Alkalinity should be 3.2–4.5 meq/L. or 7 and 12 degrees of carbonate hardness (dKH).
- CopperCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
concentration should be measured and not rise over 0.15 ppm
pH can be raised with a commercially available buffering agent
Buffering agent
A buffering agent is a weak acid or base used to maintain the acidity of a solution at a chosen value. The function of a buffering agent is to prevent a rapid change in pH when acids or bases are added to the solution. Buffering agents have variable properties—some are more soluble than others;...
or through calcium-rich substrates. A calibrated calcium reactor
Calcium reactor
In marine and reef aquariums, a calcium reactor is a device used to create a balance of alkalinity in the system. An acidic solution is produced by injecting carbon dioxide into a chamber with salt water and calcium rich media. The carbon dioxide lowers the pH by producing a solution high in...
can assist in maintaining both pH and alkalinity. Using purified water from a reverse osmosis/deionization (RO/DI) unit can prevent KH and pH fluctuation.
The nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
cycle refers to the conversion of toxic ammonia to nitrite and finally nitrate. While fish waste (urine and feces) and decaying matter release ammonia, the majority of ammonia released (approximately 60%) in both marine and freshwater aquariums is excreted directly into the water from the fishes' gills. Biological (bacterial) nitrification converts the ammonia into nitrite ions, NO2-, and then to nitrate ions, NO3-. Nitrate is readily taken up and assimilated by algae and hermatypic corals. Some nitrate is converted via an anaerobic bacterial process to free nitrogen, but this process is very difficult to maintain. In the recent past, most nitrate, which is less toxic to fishes and most invertebrates than nitrites, accumulated in the water until it was physically removed by a water change. However, many marine aquarists are now employing the use of a special section of the tank or separate tank altogether, called a "refugium." A refugium is, as its name suggests, a sheltered area that shares water with the primary, or display, tank. Refugiums usually contain a deep sand bed to allow anoxic zones to develop within them where anaerobic bacteria can convert nitrate into nitrogen gas, a useful means of nitrate removal. Various types of macroalgae can be grown and harvested from the refugium as another means of nitrate export. As refugiums become more common in marine aquaria, nitrate levels are easily manageable for even the novice hobbyist. Ammonia and nitrite should be tested regularly; any detectable levels (i.e., over 0 ppm) can be indicative of a problem. Nitrates should not exceed 2 ppm in reef tanks, or 20 ppm in fish-only tanks. It is sometimes acceptable to have a small amount of nitrate buildup, as some livestock, especially fish, are fairly tolerant of nitrate. Most corals, while able to assimilate nitrate, cannot be expected to survive, much less thrive, with high nitrate concentrations.
Other suggested tests include those for calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
, carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
alkalinity, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, and other trace elements. It is often beneficial (and necessary) for the aquarist to research the water chemistry parameters for the specific organism that is desired.
Acclimation
Acclimation is a process that is performed when adding new marine life to an aquarium, particularly for invertebrates, who lack osmoregulationOsmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too diluted or too concentrated. Osmotic pressure is a measure of the tendency of water to move...
. This process slowly introduces the organisms to the water composition of the new environment, preventing shock resulting from sudden changes in water chemistry. There are several different methods of doing this, including the use of a drip line, or of a measuring cup or other device to slowly mix water from the aquarium tank into a container with the new animal.
The drip line or trickle acclimating method is a safe and gentle way to introduce saltwater fish into a new home, and is a fairly simple one to perform. This procedure can be used to acclimate all types of marine as well as freshwater livestock. First, the fish is placed with all the bag water in a bucket or container of sufficient size for the fish to be reasonably covered with the water, and the bucket is then set on the floor next to the aquarium. Using some plastic air line tubing and an air gang valve, a siphon drip line is set up from the aquarium to the bucket. Tank water is allowed to drip slowly into the bucket, using the gang valve to adjust the drip rate, until the water dripped into the bucket equals about two to three times the original volume of the bag water. After testing the pH, salinity, and temperature of the water in the bucket to see if these parameters match that of the tank water, the fish is gently removed and placed into the tank.
Water changes
Water changes are a staple of good saltwaterSaline water
Saline water is a general term for water that contains a significant concentration of dissolved salts . The concentration is usually expressed in parts per million of salt....
maintenance. Larger (approximately 200 gallon) aquariums are much more stable and water changes may not need to take place if the nitrogen cycle
Nitrogen cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...
has fully established itself in the tank, although this is a controversial statement among aquarists. Water changes are used to maintain balance of calcium, carbonate alkalinity, and magnesium which are rapidly depleted in a reef aquarium, while also maintaining levels of other trace elements as well as removing toxic solutes which may accumulate from many different sources and are unable to be removed by even advanced filtration methods. Supplements are needed (such as calcium) when regular water changes alone are not able to maintain adequate levels, particularly those of calcium, carbonate, and magnesium. Water changes involve removing a fraction of the total volume of the aquarium, replacing that water with new pre-mixed saltwater. Pre-mixed saltwater has been dechlorinated and/or dechloraminated—typically with an additive such as bisulfite or through filtering. Water should be brought to the same temperature if more than a 5% change is occurring. Salinity should match that of the aquarium, or be dosed very slowly if altering the salinity. Aging and aerating saltwater (such as in a bucket with a powerhead
Powerhead
A powerhead, bang stick, or shark stick is a specialized firearm used underwater that is fired when in direct contact with the target. Powerheads are often used for spear fishing, and against sharks or alligators for sport, defense, or to kill nuisance animals...
or airstone) is recommended as good practice to allow the pH to stabilize.
Replacement water should be of the same source as the aquarium, whether it be reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...
(RO), de-ionized (DI), distilled or from a municipal supply, in order to avoid drastic changes in water chemistry. In cases where one is replacing a tap water-based salt mix with a reverse osmosis-based salt mix, the replacement water should be added slowly over the course of several hours to avoid sending the aquarium inhabitants into osmotic shock
Osmotic shock
Osmotic shock or osmotic stress is a sudden change in the solute concentration around a cell, causing a rapid change in the movement of water across its cell membrane. Under conditions of high concentrations of either salts, substrates or any solute in the supernatant, water is drawn out of the...
. However, large water changes are not advised under routine circumstances anyway, so this is really irrelevant. Municipal, or tap water, is not recommended for a marine aquarium as it often contains high levels of nitrates, phosphates, and silicates and other dissolved solids which fuel the growth of nuisance algaes, particularly diatoms, which appears as a rust colored powdery algae and grows in the overabundance of silicates present in all tap water. Water filtered by a four stage process including mechanical, carbon, reverse-osmosis, and de-ionizing components is recommended as this can provide the easiest route to absolutely pure water. Four and Five stage RO/DI filtration units can be obtained for as little as $100 and are a cost effective means of converting tap water into water usable in a marine aquarium.
Conservation
Almost all species kept in marine aquaria at this time are caught in the wild, although tank-raised specimens are becoming increasingly common as a viable alternative. Only a few species such as clownfishClownfish
Clownfish or anemonefish are fishes from the subfamily Amphiprioninae in the family Pomacentridae. Twenty-eight species are recognized, one in the genus Premnas, while the remaining are in the genus Amphiprion. In the wild they all form symbiotic mutualisms with sea anemones...
are captive-bred on a commercial scale. Much collecting is done in Indonesia and the Philippines, where use of cyanide and other destructive collection methods, while discouraged, is unfortunately common. The majority of live rock is also harvested in the wild, and recent restrictions on this harvest in Florida have caused a shift to Fijian and aquacultured rock. Natural rock, because it is created by coral polyps, takes many years if not centuries to form, and is a vital habitat for countless marine species; thus, commercial-scale harvesting of naturally-occurring live rock has been criticized by conservationists. Additionally, many animal species sold to hobbyists have very specific dietary and habitat requirements that cannot be met by hobbyists (e.g. Labroides genus wrasses, the moorish idol
Moorish Idol
The moorish idol, Zanclus cornutus , is a small marine fish species, the sole extant representative of the family Zanclidae in order Perciform. A common inhabitant of tropical to subtropical reefs and lagoons, the moorish idol is notable for its wide distribution throughout the Indo-Pacific...
); these animals almost inevitably die quickly and have markedly reduced lifespans compared to wild specimens. Often these specific environmental requirements cause improperly housed lifestock's color and appearance to be poor. These issues are often downplayed by individuals and organizations with a financial interest in the trade. Hobbyists who support conservation should buy only certified net-caught fish (although ensuring the legitimacy of such claims can be difficult) or captive-raised fish, as well as farmed corals and to support legitimate reef conservation efforts. The majority of corals can be "fragged", whereby a portion of a larger captive coral is separated and can subsequently be raised into an individual specimen, allowing for coral propagation within the domestic aquarium; the trade in frags (i.e. fragments) offers a fantastic opportunity for marine aquarists to obtain new and unique corals while limiting the impact on the natural environment. Rare species and those without a history of being successfully kept in captivity should be avoided.
Commercial development
Various businesses have commercialized fishkeeping. With the advent of large scale business operations focusing on breeding massive quantities of specimens, marine fishkeeping has become much more widespread than ever before. Perhaps the biggest disincentive to marine fishkeeping, in comparison to freshwater, is the initial setup cost. A 100 US gallon (400 L) reef tank full of coral and equipment can cost in excess of $2,500 US, although a budget-minded home hobbyist could spend less than half of this and still get a satisfactory result.Further reading
- Advanced Marine Aquarium Techniques, by Jay Hemdal
- The Conscientious Marine Aquarist, by Robert Fenner
- Invertebrates: A Quick Reference Guide, by Julian SprungJulian SprungJulian Sprung is an American writer on marine aquarium fishkeeping. He is an alumnus of the University of Florida where he studied zoology, graduating in 1988....
- Corals: A Quick Reference Guide, by Julian Sprung
- Reef Invertebrates: An Essential Guide to Selection, Care and Compatibility, by Anthony Calfo and Robert Fenner
- Aquarium Corals: Selection, Husbandry, and Natural History, by Eric H. Borneman.
- Natural Reef Aquariums: Simplified Approaches to Creating Living Saltwater Microcosms, by John H. Tullock
External links
- RTAW Reefpedia, a Reef Keeping wiki maintained by the Marine Aquarium Societies of Australia
- Reef Hobbyist Online, a Reef Aquarium electronic magazine with articles written by expert marine aquarists