DESC: Marineland Magnum Micron Cartridge #047431014008Excellent for polishing your aquarium water. This cartridge will pull out the finest of particles, resulting in a crystal clear aquarium. Can be used with diatomaceous earth, but make sure that your filters instructions specifically state that it is designed to be used as a diatom filter. For use with the Magnum 200, 220, 330, 350, and H.O.T. Magnum 250 only. - Filtration