Phosphate Reducer is designed to reduce and eliminate both ionic & chemically bound phosphate in marine/reef aquariums. Phosphate exists as ionic and chemically bound by calcium, this causes fluctuations of calcium, stunted coral growth rates as well as the false reading of low phosphate due to the inability for test kits to be able to test for bound phosphate. Media & carbon sources remove the ionic phosphate but take long to remove the bound phosphate due to its high stability. Our phosphate remover will precipitate out both ionic and chemically bound phosphate and place it in existing filter wool/socks. Note: A fine white film building on the glass indicates that you are overdosing, we recommend adjusting your dose and using our White Film Remover to safely clean any build up.