Our Fluval Carbon provides large amounts of surface area for absorption of impurities. It effectively removes heavy metals, odors, discolorations, organic contaminants and pollutants to leave your aquarium water crystal clear and sparkling. Contains premium research grade low-ash carbon. Highly porous and absorbent to last longer. Does not raise phosphate levels. Contains three replacement packs. For use with Fluval Canister Filters: 105, 205, 305, 405, FX5, 104, 204, 304, 404, 103, 203, 303 and 403. For freshwater and marine environments.