PR-10,000 is a highly concentrated rare-earth phosphate remover formulated to react with phosphates in the water, allowing them to be removed from solution. It reacts with all known types of phosphates on contact and hardens them into a fine precipitate, which falls out of solution. The inert phosphates then floc out, to be vacuumed or filtered out. It causes cloudiness, which can last anywhere from a few hours to a few days. Because of PR-10,000's concentration, a little goes a long way.