Penn Plax Cascade 700/1000 GPH Canister Filter Aquarium Bio Sponge Replacement, 1 Pack

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 700 / 1000 filter tray without any gaps ?which could allow pollutants to re-enter the water. International products have separate terms, are sold from abroad and may differ from local products, including fit, age ratings, and language of product, labeling or instructions.