Keep your aquarium clean and fresh at all times when you use Aqueon Replacement Filter Cartridges, Large. These are ready-to-use, preassembled products that install in seconds and help create crystal-clear, healthy water for your aquarium. The 3-pack of Aqueon filter cartridges, large contain a patented, dual-sided replaceable dense-floss material that penetrate out more particles and debris. These contain activated carbon for removal of odors, discoloration and toxic impurities. The aquarium filter cartridges are meant for use with fresh or saltwater homes for your fish. It is recommended you change these every four to six weeks to maintain the purest possible aqua for your pet. These are intended for use with Aqueon Power Filters 20, 30 and 55. For a fresher aquarium, reach for Aqueon Replacement Filter Cartridges, Large