PhosBan from Two Little Fishies is a favored chemical filter media because it will not leach substances back into your aquarium. Largest adsorption capacity of any phosphate filtering media. Ferric oxide hydroxide-based granules also adsorb organics and other pollutants. Use just like activated carbon; filter bag included. Non-toxic and lasts several months in typical aquariums. Great for saltwater and freshwater aquariums. For best results, use with a TLF Phosban Reactor 150 or 550.