Pool Magic+PHOSfree is ideal for treating your pool at the beginning and end of each season as well as reducing phosphates at any time as the first step of Natural Chemistry's Clear, Perfect Water Program. Pool Magic+PHOSfree contains all-natural enzymes that break down non-living organics to make opening and closing fast and easy. A quick clean-up to start off the season and to prevent non-living organic staining and phosphate build-up. Specifically formulated for cold water application Speeds clean up and readies the pool for trouble-free maintenance. All benefits of Pool Magic and PHOSfree combined. It can be used under pool winter covers, an ideal product for mesh-covered pools. End-of-season application reduces off-season waterline rings and staining of pool surfaces by non-living organic contamination.