I would like to know the optimum temperature to keep propane at in a 30 lb and 50 lb tank. I have used a warm bath to keep the tank from freezing but I made it too warm because the propane did not flow. So I want to know what the water temp should be kept at in order to keep the propane fuel flowing properly. And is there a "sliding temp scale"? In other words as the tank empties what should the temp be at 100% full, 75% full, 50% full, etc..Thanks