Penn Plax Cascade 1200 / 1500 GPH Canister Filter Aquarium Bio Sponge Replacement; 1 Pack Keep your water clean and clear with the replacement bio sponge for use in the Cascade 1200 Model CCF4UL or 1500 Model CCF5UL canister filter. The bio sponge filter removes ammonia and nitrites from your aquarium tank keeping your aquarium clean; healthy; and odor free. Filter sponge optimizes the colonization of beneficial aerobic bacteria which prevents the water from becoming cloudy and harming fish. Perfectly cut to fit into the Cascade 1200 / Cascade 1500 filter tray without any gaps which could allow pollutants to re-enter the water. Genuine Penn Plax replacement cartridge for Cascade 1200 / Cascade 1500 models. When used together; the filter and bio sponge provide maximum protection against water pollutants.