AquaPill 90122APL 4" 420mL WinterPill® Pool Winterizing Formula is an all-in-one formula that makes winterizing your pool faster and easier than ever! WinterPill® clarifies the pool. water and helps reduce scaling and staining. WinterPill® is enzyme enhanced and controls non-living organics to control waterline ring and enhance filter performance. WinterPill's® patented pre-measured release delivery system effectively helps maintain clear water during the off season. WinterPill's® concentrated formula can be used will all sanitizers, is compatible with all pool surfaces and will not affect pool chemistry.