Calculator
pH & Total Alkalinity Calculator
pH and total alkalinity move together, which is why so many pools bounce between cloudy and etched. Get the dose for each adjustment, and the order to make them in.
gal
ppm
ppm
Result
Add 9.00 lb baking soda
Correct total alkalinity first, then re-test and fine-tune pH. Add acid slowly over a return jet with the pump running.
- Step 1 — raise TA
- 9.00 lb sodium bicarbonate
- Step 2 — lower pH to 7.5
- 18.0 fl oz muriatic (31.45%)
- Step 2 — raise pH to 7.5
- Not needed
- Retest after
- 6 hours of circulation
How this is calculated
- Targets: pH 7.4 to 7.6, total alkalinity 80 to 120 ppm (60 to 100 ppm on a salt pool, which trends alkaline).
- Correct total alkalinity first, then fine-tune pH. Adjusting pH while TA is out of range means chasing the same reading every week.
- About 1.5 lb of sodium bicarbonate per 10,000 gallons raises total alkalinity roughly 10 ppm.
- About 10 fl oz of 31.45% muriatic acid per 10,000 gallons lowers pH roughly 0.2 at TA 100; the higher the alkalinity, the more acid the same drop takes.
- About 6 oz of soda ash per 10,000 gallons raises pH roughly 0.2 and nudges alkalinity up with it.
- Add acid slowly over a return jet with the pump running, then retest after 6 hours of circulation.
Figures follow commonly published residential pool references and are guidance, not a substitute for testing your own water. Always follow the product label and add one chemical at a time.
Frequently asked
- Why does my pool pH keep rising?
- Aeration drives pH up: waterfalls, spa jets, salt-cell hydrogen and even a fresh plaster surface all push it higher. High total alkalinity accelerates it, so lowering TA into range is what actually stops the weekly climb.
- Can I add acid and chlorine at the same time?
- No. Adding acid directly into a freshly chlorinated area risks a violent reaction and off-gassing. Separate the additions by at least 30 minutes of circulation, and never mix chemicals in the same bucket.
- What happens if alkalinity is too low?
- pH becomes unstable and swings after every rain or chemical addition, and the water turns aggressive toward plaster, grout and metal components. Below about 60 ppm, expect etching and corroded equipment over time.
- Is high alkalinity a problem if pH is fine?
- Yes. High TA buffers the water so strongly that pH drifts up continuously and scale forms on tile and the salt cell. Lower it with measured acid doses across several days rather than one large addition.
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