The Aquapill WinterPill is a multipurpose pool winterizing product that will help clarify the water, reduce scaling and staining during the winter season, and also improve filter performance and reduce time spent opening the pool at start up. Use this to help control non-living organics and prevent waterline ring buildups when the circulation system is not running. It is pre-measured with a release system designed to maintain clear water while the pool is not in operation. The Aquapill WinterPill is compatible with all sanitizers and pool surfaces, and does not affect pool chemistry.