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What’s the Next Step for Your Pool’s pH?

Reviewed 2026-04

Work on pH one small addition at a time. Use measured alkalinity and CYA for the dose, plus recent FC to confirm that your pH test is valid.

See how the calculations work in our methodology

HOCl percentages for water without stabilizer do not describe a pool that contains CYA. CYA changes the balance of active chlorine; use stabilized-water guidance when assessing chlorine activity.

Safety:Safety: Wear gloves and eye protection as directed by the label. If dilution is required, add acid to water; never add water to concentrated acid. Never mix chemicals.
Example volumes (gallons):

Correction targets here: pH 7.2–7.6. The starting target is pH 7.4.

Use measured TA to account for how your water resists a pH change. Acid lowers TA along with pH; you’ll see an estimate of that drop in the result.

CYA also buffers pH and affects the acid estimate. Enter 0 only if measured or known absent. If you haven’t measured CYA, leave it blank and test before dosing.

Does your pool have a salt chlorine generator?

Which acid will you use?

You can choose dry acid only after confirming your pool has no salt cell. Never use sodium bisulfate with a Pentair IntelliChlor salt cell, as its manual directs. Its by-products can build up and damage the cell; Hayward also warns against dry acid. If you are unsure whether your pool has a salt cell, use muriatic acid and follow its label.

Use the percentage printed on your bottle; the liquid amount uses that strength and its modeled density. Buy liquid acid locally and follow the label’s handling and application directions.

Confirm your inputs

Before you use a dose, compare every input with your fresh tests and measured pool volume. Confirm each example value only after you’ve checked it. When you change a value, you’ll need to confirm it again.

Frequently asked questions

Why can I only choose a pH target from 7.2 to 7.6?

The 7.2–7.6 choices are targets for a correction. A pH result alone doesn’t clear the pool for use. Before anyone swims, check that pH is 7.2–7.8, FC meets the minimum for measured CYA, the water is clear and the label’s re-entry conditions are met.

Can I use a pH reading taken after shocking?

High free chlorine can distort a phenol-red pH result. Follow your test-kit instructions for interference limits: this tool blocks drop-test and strip-based doses at FC 10 ppm or above. Take a fresh reading within those limits, or use a calibrated meter suitable for the sample. Never improvise a neutralizing treatment for the test.

Why is the dose only one small pH step?

Start small so you can measure how your water responds. Each dose models a change of at most 0.2 pH units using measured TA and CYA. The model assumes 25°C water and leaves out borate buffering, gas exchange and precipitation. Circulate for at least four hours, or longer if the label requires, then retest pH and TA before calculating another step.

Will soda ash also raise my alkalinity?

Yes. Soda ash adds carbonate, so TA rises along with pH. Your water’s buffering sets the amount needed; a fixed ounces-per-pH-change rule misses that. When pH is low and TA is already high, aeration can raise pH without adding alkalinity. Measure again before deciding on a chemical addition.

What should I check before using acid or soda ash?

Choose a product labeled for pools and follow its protective equipment, mixing and application directions. Never mix chemicals or add water to concentrated acid. Enter liquid acid strength from your bottle and buy it locally at that strength. You can select dry acid here only after confirming there’s no salt cell, because some cell manuals prohibit it.

Alkalinity Calculator →Chlorine Calculator →

How we calculate this
Your result uses the formulas explained in our methodology. Read the assumptions for your calculation before you use the result.