Antiphos FE – 500 ml (or 0.75 lbs) is a phosphate and silicate remover for controlling algae growth in fresh and saltwater aquariums. Antiphos Fe is an ideal medium for selectively extracting phosphate and silicate from aquarium water, thus counteracting unwanted algal growth. Antiphos Fe is a highly active granular ferric oxide (High Capacity GFO) or iron based product containing no aluminum and is completely nontoxic to aquarium plants and animals. The binding capacity of Antiphos Fe is app. 10g phosphate/kg. Subject to the conditions 500 ml of Antiphos Fe will treat a normally populated 80 gal. aquarium for app. 3-6 months.