The leading hot tub chlorine sanitizer. Say goodbye to bacteria and say hello to clean water!When used as directed, this product is effective as a spa and hot tub water disinfecting agent.Use: Use one teaspoon of this product per 100 gallons of water. May be needed on a nightly basis in a heavily used spa or as infrequently as once a week in a moderately used spa. Check levels of chlorine using your standard Chlorine test strip. Keep a residual of 3-5 ppm of available chlorine for optimal hot tub balance.