Aqua Chem Shock Plus is an all-in-one shock that kills organic contaminates, improves filtration, clarifies water and will not increase pH levels. There"s no need to pre-dissolve and swimming can be resumed as soon as 15 minutes after adding. Shock Plus reduces chlorine odor and eye irritation, and will not increase pH. For use in all pools including vinyl, plaster and fiberglass. Reduces organic contaminants, clarifies water and enhances filtration. One pound treats 12,000 gallons of water. Use weekly.