Granular Ferric Oxide (also known as GFO, GHF, Granular Ferric Hydroxide or iron oxide hydroxide) is a reddish brown, granular-shaped filter media that is one of the most common and effective methods of reducing phosphate in aquariums, ponds and swimming ponds.
Elevated phosphate levels can cause a variety of undesirable effects, including increased green algae growth and decreased growth of calcifying organisms such as corals and coralline algae. GFO is generally regarded as a very safe and efficient way to reduce phosphates and silicates from the water. Maintaining low phosphate levels helps prevent algae outbreaks and control algae growth in reef tanks. In addition to reducing phosphate, GFO also absorbs fluoride, molybdenum, selenium, antimony, arsenic and more.
Start with small amounts, rinse carefully and change frequently. You’ll have great results!