Pool pH Calculator
The sweet spot is 7.4-7.6 ppm. Below 7.2 your water eats eyeballs and equipment; above 7.8 chlorine goes lazy and scale forms. Pick what you need below.
How the math works
- Soda ash: about 6 oz per 10,000 gallons raises pH roughly 0.2 (with total alkalinity near 100 ppm).
- Borax: about 16 oz per 10,000 gallons for the same 0.2 move. Slower but gentler on total alkalinity.
- Muriatic acid (31.45%): a starting dose of about 1 pint (16 fl oz) per 10,000 gallons lowers pH about 0.2. The real move depends heavily on your total alkalinity - always retest and repeat in small steps.
Safety rules that are not optional
- Always add acid to water, never water to acid. Pre-dilute in a bucket of pool water and walk it around the deep end.
- Never mix acid and chlorine - keep at least 30 minutes of pump run time between them.
- Do not swim until pH is back above 7.0 and free chlorine is back in range.
- pH keeps drifting up? Test your total alkalinity first - high TA is the usual culprit, and acid fixes TA, not just pH.
- pH swinging both ways? Cyanuric acid below 30 ppm makes pH unstable. Check your CYA.
Frequently asked questions
How much soda ash raises pH by 0.2 in a 10,000 gallon pool?
About 6 oz by weight (roughly 3/4 of a cup). A 20,000 gallon pool needs about 12 oz for the same move. Retest after one full pump cycle before adding more.
Why did my pH not move after adding acid?
Usually total alkalinity is very high - it acts as a pH buffer. You may need several small acid doses over days, or the pH reading is being distorted by a stale test kit. Replace reagents yearly.
Can I just use baking soda to raise pH?
Baking soda barely moves pH but raises total alkalinity a lot. Use it when TA is low and pH is fine. For pH that is genuinely low, soda ash or borax is the right tool - see the alkalinity calculator for baking soda doses.