Fluval water carbon pads are uniquely designed to fit the fluval fx5 and fx6 high performance canister filterr 2 pads per packr for freshwater and marine environmentsr fluval carbon impregnated foam pads are specially designed for fluval fx56 high performance canister filters these carbon impregnated pads capture micro particles as the water passes through the added carbon removesodouranddiscolourationas well as heavy metals and organic contaminants