Hot Tub Things Oxidizing Spa Shock 2.2 Pounds - Prevents Organic Buildup and Cloudy Water Use shock weekly to control and prevent organic buildup that causes cloudy water! America's #1 Trusted Brand of Hot Tub Chemicals Safety Tested to Assure Quality, Guaranteed Performance Formulated Exclusively for Hot Tubs And Made from the Purest Chemicals Available Compare to Leisure Time Renew Add 2 ounces per every 300 gallons of water. NOTE: Apply the required amount evenly throughout the spa with the pump running. Run the pump for at least 30 minutes. Turn the jets on and off once or twice after adding the Oxidizing Spa Shock to make sure its evenly spread.