High pH is lowered with muriatic acid, dosed by volume and the size of the drop. Acid demand also depends on total alkalinity — higher TA needs more acid for the same pH change.
The example
20,000 gal, lower pH 0.4.
| A | B | |
|---|---|---|
| 1 | Item | Value |
| 2 | 2 × 0.4 × 16 | — |
| 3 | Muriatic acid | → ~12.8 fl oz |
The formula
The formula:
How it works
How it works:
- Use an acid constant (fl oz per 10,000 gal per 0.1 pH, adjusted for alkalinity).
- Scale by volume (10,000s) and the pH drop you want.
- Higher total alkalinity buffers pH — it takes more acid for the same drop.
- Add acid diluted and slowly, retest after circulation; never overshoot.
Educational use only — not chemical-safety or professional advice. Pool chemical dosing varies by product strength, water chemistry, and local rules. Always follow the product label, add chemicals to water (never water to chemical), test before and after, and never mix chemicals. Verify with a professional.
Try it: interactive demo
Gallons, pH drop, acid constant (fl oz/0.1 pH per 10k).
Variations
In cups
Fl oz ÷ 8:
Alkalinity adjustment
Scale by TA:
Add slowly (split)
Half now, retest:
Pitfalls & errors
Alkalinity matters. Higher TA needs more acid for the same pH drop.
Go slow. Add diluted, circulate, retest — don’t overshoot.
Never mix. Acid and chlorine together are dangerous — follow the label.
Practice workbook
Frequently asked questions
How do I calculate muriatic acid to lower pH in Excel?
Why does alkalinity matter?
How should I add acid?
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