Natures Pure Pool Purifier is a combination of minerals that actively sanitize and reduce algae. The specifically designed cartridge is infused with the Natures Pure minerals which immediately disperse and build and effective residual throughout the entire pool. The mineral blend reduces algae, freeing up chlorine to work more effectively. As the pool circulates, the minerals are refreshed as the water passes through the cartridge. Natures Pure Pool Purifier works collaboratively with constant low levels of chlorine. Compatible with any type of chlorine system.