Activated Carbon Filter Media Pad Aquarium Filter Media Pond Canister 18" x10" Size:2 Pack FEATURE: Activated carbon impregnated filter pad effectively traps large particles, removes discoloration, odor, pollutants, and harmful chemical to keep your aquarium crystal clear DIY Cut-to-fit filter pad, good to use in freshwater and saltwater aquariums. Works with all filters: canister, hang-on filter, wet/dry, pond filters, DIY filters Size of each pad: 18"x 10" , Includes: 2 pack of filter pad To ensure optimum performance, replace the filter pad every three to four weeks depending on waste load of the fish tank Includes: 2 pieces of filter pad