Fluval A-1500Phosphate Remover contains ferric oxide, an iron-based phosphate binder ideal for use in aquarium filters150 grams removes up to 20 mg/L (ppm) of phosphate in a 50 U.S. gallon aquariumFor freshwater and saltwater aquariumsWill not affect pH or hardnessFluval Lab Series Phosphate Remover rapidly adsorbs large quantities of phosphate, silicate and dissolved organics without leaching adsorbed substances. Maintaining low levels of phosphate will result in cleaner, healthier aquarium water while allowing corals to efficiently absorb the calcium they require to grow and reproduce.