Fluval 20 Media Maintenance Kit BioMax Filter Insert provides an optimal environment for the colonization and growth of beneficial bacteria, which is essential for effective biological filtration and water purification Activated Carbon Filter Insert improves water clarity in fresh and saltwater aquariums and provides superior adsorption qualities which eliminate odors, discoloration and impurities Foam Filter Insert is a mechanical filter media that effectively removes particles and debris from aquarium water Safe for fresh and saltwater aquariums