pH Adjustment Calculator

pH is how acidic or basic your water is; the comfortable, plaster-safe range is about `7.4–7.6`. To lower pH you add acid — muriatic acid (`31.45%` hydrochloric acid) or dry acid (sodium bisulfate). To raise it you add soda ash (sodium carbonate). The calculator reads your current and target pH, your total alkalinity, and your volume, then estimates the dose.

Why alkalinity matters: alkalinity is the buffer that resists pH change, so the same pH move takes more acid in a high-alkalinity pool than a low one. The estimate is anchored on a published service rule — about `1` quart of `31.45%` muriatic acid lowers pH roughly `0.5` in `10,000 gal` at alkalinity `100` — and scales that by your volume, your pH change, and your alkalinity. Dry acid is shown as the stoichiometric equivalent, and soda ash uses the matching rule for raising pH.

Treat every number here as a **starting estimate, not a prescription**. Real pH response is non-linear, and the surest method pros use is an acid-demand test. Add about three-quarters of the calculated amount, run the pump, wait, and retest before adding the rest. Always add acid to water, never water to acid, and pour it slowly over a return jet in the deep end.