Minerals, such as silver and copper, 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. Nature2 offers these benefits for your pool: Controls Algae Destroys Bacteria Won't Stain Your Pool Nature 2 cartridges are made to fit inside your pool filter cartridges for easy use. “Swim Pure” Style Cartridges are specially designed to fit inside Hayward® brand cartridge filters “Cartridge Filter (CF)” Style Cartridges are designed to fit inside most all other brand cartridge filters Replace your pool mineral cartridge every 6 months to keep your pool clean, clear, and algae-free.