Carbon Dioxide is a popular product used to lower pH in swimming pools in conjunction with an active disinfectant that is either calcium hypochlorite, or preferable sodium hypochlorite. The CO² regulator can only be used with a chemistry controller that –at a minimum- measures and regulates the pH and oxidation reduction potential (ORP) of the water and opens and closes a solenoid valve regulating the release of CO² into the pressure-side of the circulation system (after the heater).
When CO² is mixed with water a mild acid –carbonic acid- is produced thus reducing pH. It’s best to run a by-pass line off the pressure-side of the filtration system after the filter thus allowing the operator to regulate the amount of flow, while simultaneously creating an excellent contact chamber (in the by-pass line) for the carbonic acid to dilute in solution prior to being ejected into the pool. At Aqua Design International we believe CO² is a particularly attractive pH control tool to use on resorts as well as limited service hotel applications for two reasons. First, there is no need to store muriatic acid, or sulfuric acid; all that is needed is a tank (50-400lbs) that is either exchanged or filled with CO² when needed. Second, the cost of CO² is an astonishingly economical 35 cents per pound.