Natural Chemistry Pool Magic Spring & Fall + Phos Free, 4 Liter

Concentrated cold-water formula makes opening your pool a breeze. Preserves pool liners and finishes, helps reduce staining and the need to acid wash. In the fall when you close your pool, one application of Pool Magic will provide a residual level of enzymes in your water over the off-season, which prevents water line rings, etc., from forming. When you fill your pool in the spring this dilutes the concentration, so the additional spring or opening dose is necessary for fresh fill water. Recommended Dosage: 1-2 weeks before closing, add 1L to skimmer.