Muriatic Acid Pool Calculator
Enter your pool gallons and current and target pH to estimate the muriatic acid needed to bring pH down. Read the safety notes before you dose.
What your result means
This is a rule-of-thumb dose: about 12 fl oz of muriatic acid per 10,000 gallons drops pH by 0.2. Safety first: acid is corrosive, so wear gloves and eye protection, always add acid to water (never water to acid), pour it slowly into the deep end with the pump running, and never mix it with chlorine. Recheck pH after 4 to 6 hours before adding any more.
How to use this calculator
- Test current pH with kit or strips.
- Target pH: 7.2-7.6 (7.4 ideal).
- Enter pool gallons.
- Read ounces of muriatic acid needed.
- Add acid in deep end with pump running, brush to disperse.
The formula
The dose scales with pool size and how far pH has to drop, using the rule that 12 fl oz per 10,000 gallons lowers pH by 0.2. Eight ounces is a cup.
Worked example
Say you've got a 15,000 gallon pool reading pH 8.0 and you want 7.4, a 0.6 drop. That works out to about 54 fl oz of muriatic acid, just under 7 cups.
Pool pH targets
| Item | Value |
|---|---|
| Ideal pH | 7.2 – 7.6 (7.4 target) |
| Dose rule | 12 fl oz / 10,000 gal = -0.2 pH |
| 1 cup | 8 fl oz |
| Recheck after | 4 – 6 hours |
Tips & gotchas
- Muriatic acid lowers both pH and total alkalinity.
- Ideal pH is 7.2 to 7.6, with 7.4 the sweet spot.
- Add it slowly in the deep end with the pump running.
- Wear gloves and eye protection; the acid is corrosive.
- Recheck pH after 4 to 6 hours before adding any more.
Frequently asked questions
How much muriatic acid to lower pool pH?
About 12 fl oz per 10,000 gallons drops pH by 0.2.
What's the right pool pH?
7.2 to 7.6 is ideal, with 7.4 the target.
Is muriatic acid dangerous?
Yes, it's corrosive. Wear PPE, never mix it with chlorine, and store it somewhere cool and dry.
Can I use dry acid instead?
Yes, sodium bisulfate. It's safer to handle but less powerful per pound.
Why is my pool pH always high?
High alkalinity, calcium deposits, or aerated water all push pH up.
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