4 in 1 Formula: Kills bacteria and won’t impact pH. Clears cloudy water. Destroys contaminants. Improves filter performance Swim-ready in 15 minutes: Fast dissolving formula works quickly so you can treat and swim in just 15 minutes Compatibility: This product is safe for all swimming pool surfaces, including vinyl, plaster, fiberglass, and tile. Usage: Use 1 lb. per 12,000 gallon of water. Shock pool weekly and after heavy use, high temperatures, or rain. Clorox Pool App: Test like an expert anytime, anywhere with the Clorox Pool App. Solve common swimming pool problems and get personalized product and dosage recommendations