Pool Chemical Calculator

Balanced pool water keeps swimmers comfortable, protects pumps and heaters from corrosion, and lets your sanitizer actually do its job. This tool translates your pool's size and current readings into the specific amounts of chemical needed to bring pH, chlorine, and alkalinity into range. Getting those numbers right also heads off the cloudy water, algae blooms, and skin irritation that come from levels left out of balance.

CDC recommends keeping pool water at pH 7.0-7.8 with at least 1 ppm of free chlorine, or at least 2 ppm if the water contains cyanuric acid or you use stabilized chlorine such as dichlor or trichlor; hot tubs need at least 3 ppm. You enter the current readings and your targets (pH 7.4 and 2 ppm by default). A pH above the target is lowered with muriatic acid (31.45%) and one below it is raised with soda ash. Chlorine is dosed as 12.5% liquid chlorine at 10 fl oz per 1 ppm per 10,000 gallons, and alkalinity is raised toward 100 ppm with baking soda at 1.5 lb per 10 ppm per 10,000 gallons. Both rates are in line with the Lucas County (Ohio) Health Department's dosing chart, which lists 10.7 fl oz of 12% liquid chlorine per ppm and about 1.5 lb of sodium bicarbonate per 10 ppm. The same chart puts the pH dose at about 12 oz of muriatic acid to lower pH by 0.2 in 10,000 gallons and 6 oz of soda ash to raise it by 0.2, and the calculator uses those rates (6 fl oz of acid or 3 oz of soda ash per 0.1 pH per 10,000 gallons). The chart notes that the real dose depends on a demand test and the alkalinity, so add pH chemicals in portions and retest before adding the rest.

Test with a reliable kit before you add anything (CDC recommends a DPD kit and testing chlorine and pH at least twice a day), and retest 4-6 hours after dosing, as the calculator's steps say. Never mix pool chemicals with one another: CDC warns that chlorine products mixed with acid can release toxic gas, and that water should never be poured onto a pool chemical, because the reaction can be violent. Going slow pays off as well: small, repeated adjustments with a re-test in between beat dumping in a large dose at once, and that is doubly true for pH, which tends to drift.