Aqua Dreams Simplicity GFO Phosphate Remover - 1 lb.
Granular ferric oxide, or GFO, is a commonly used form of chemical filtration for the reef and saltwater aquarium. Chemical filtration, as the name suggests, purifies water by binding up impurities at the molecular level. As water is sent through the medium, the surface of the medium forms chemical bonds with dissolved compounds, thus removing them from the water. Different chemical filtration media target different compounds. The goal of GFO, specifically, is to help control phosphate. Use approximately 1/2 cup per 25 gallons, use a phosphate test kit to monitor levels and adjust / replace media as needed. Use as directed, replace every 60-120 days depending on phosphate and overall bio-load of the aquarium.