Hayward's Standard CO2 pH control system regulates the injection of Carbon Dioxide, a natural non-corrosive gas to replace hazardous liquid acid in chemical treatment of swimming pools, spas, and water features. The CAT 1000 implements chemical feeding in proportion to demand, ensuring precise pH maintenance without overfeeding. Regulates the injection of carbon dioxide, a natural non-corrosive gas to replace hazardous liquid … Hayward residential Co2, pH control system is simple to install and operate. Read honest and unbiased product reviews from our users. please update your current version of Internet Explorer or try using a different browser. Hayward websites have been developed in compliance with standards for Internet Explorer 10 or later. Find helpful customer reviews and review ratings for Hayward AC003 Residential CO2 pH Control System at Amazon.com. When dissolved in water, CO2 forms carbonic acid (H2CO3), a relatively mild acid which lowers the pH of the water while increasing total alkalinity. IE9 and older versions are not supported. IE9 and older versions are not supported. The CAT 1000 ® automated controller monitors and automatically maintains healthy pH balance, protecting the pool surface and equipment while promoting bather comfort.