Provides fast and easy opening and closing! Use Pool Magic + PHOSfree at both opening and closing to reduce the time and effort needed to open the pool. Works great with mesh covers! Specifically formulated for cold water application Speeds clean up and readies the pool for trouble-free maintenance. All the benefits of Pool Magic Spring & Fall and PHOSfree combined 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 surface by non-living organic contamination.