Defender is the bigger option filter for larger pool water volume. This precoat filter is known for its excellent filtrate quality and low backwash water requirement. This filter yields a very large filter area because of the use of capillary shaped filter surfaces. Perlite, which is harmless, is used as the filter media for regenerative filters and a vacuum conveyor is used for the dust free application directly from packaging into the vessel. When the perlite becomes loaded, the Defenders regenerate by mechanically “bumping”, a process in which no water is lost. Since nobody really likes backwashing, you can eliminate this process. Defender filters automatically bump for a fresh start!