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 so it installs 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. Pool Size: 5000 - 25000 gal. Size: Size: 4'' x 8''