Fluval Carbon BagsHagen Fluval Carbon 3 packs contain high purity activated carbon for both freshwater and marine aquarium filtration. The inner matrix structure provides a large porous area that permanently traps organic waste while removing liquid wastes such as urine, dyes or many other impurities from the water. The result is sparkling clear aquarium water. Chemical filtration media for all external filters Improves water clarity and color and removes odors For use