SeaKlear AquaPill Summer Pill to Enhance Sanitizer Performance, 4" This amazing all-in-one formula is an exclusive 4-part blend containing a clarifier to maintain brilliant shimmering water, a scale inhibitor to prevent scale build-up on pool surfaces, and a stain inhibitor to prevent iron, copper and manganese stains Prevents scale build-up, metal stains and enhances sanitizer performance Simply punch the chemical dispensing hole and place in your skimmer Treats up to 30,000 gallons and safe on all pool surfaces and filter systems