Nature2® W26755 5-25K gals N2CM Premium M25 Cartridge uses safe, elemental mineral ingredients to create pool water that is noticeably cleaner, clearer and softer. Minerals such as silver and copper have long been known for their sanitizing antimicrobial properties. With Nature2® cartridges, we bring that natural sanitization to your swimming pool. Nature2® is proven to allow you to reduce chlorine use up to 50% and is guaranteed to kill bacteria and control algae. Whether you use chlorine or salt water, Nature2® works to optimize your system and reduce the use and effects of traditional harsh chemicals. That means less red eyes, itchy skin, and unpleasant odor. Enjoy pool water, naturally