Keep your tank clean and running properly with the API Filstar XP Microfiltration Aquarium Canister Filter Filtration Pads. These pads are made of thick foam to filter out the finest particles from your underwater buddy’s water. It can be used with both freshwater and saltwater aquariums and should be replaced at least once a month or every time the water is changed. Designed for use with API FILSTAR XP canisters filters， consider these filtration pads as a solid option for making sure your aquarium is as clean as it can be.