Zodiac Nature2 Swimpure 3" 5- 25K Gallon Pools. Nature² contain minerals, such as silver and copper, that have long been known for their sanitizing antimicrobial properties. Nature2 brings the benefits of these safe elemental ingredients to create pool water that is noticeably cleaner, clearer, and softer. Replace your pool mineral cartridge every 6 months to keep your pool clean, clear, and algae-free. SwimPure Cartridge Filter Inserts reduces the need for chlorine by as much as 80% while maintaining safe algae-free water. With a reduction in chlorine or other sanitizers, comes the elimination of stinging eyes, dry skin and bleached swimsuits. The SwimPure canister slips inside Hayward's cartridge element. Istalls in seconds, but lasts a full 6 months. Nature2 and Hayward have teamed up to design the SwimPure system so that it operates perfectly with Hayward's family of cartridge filters. Dimensions: 3" x 11" Pool Size: 5,000 - 20,000 gal.