How Much Muriatic Acid to Add to Your Pool (Dosing Guide)
Need the exact dose right now? The tables below cover pH reduction and total alkalinity reduction by pool size. For full safety instructions and application details, see our complete muriatic acid pool guide.
Video guide
Video: “How to Safely Add MURIATIC ACID to Your Pool” by Swim University
Muriatic acid dosing for pH reduction
These doses are for standard 31.45% muriatic acid (pool grade). The pump must be running when adding acid for pH reduction.
| Pool Size | Lower pH 0.2 | Lower pH 0.4 | Lower pH 0.6 | Lower pH 0.8 |
|---|---|---|---|---|
| 5,000 gal | 5 oz | 10 oz | 15 oz | 20 oz |
| 10,000 gal | 10 oz | 20 oz | 30 oz | 40 oz |
| 15,000 gal | 15 oz | 30 oz | 45 oz | 60 oz |
| 20,000 gal | 20 oz | 40 oz | 60 oz | 80 oz |
| 25,000 gal | 25 oz | 50 oz | 75 oz | 100 oz |
Important notes:
- Add acid slowly around the pool perimeter with the pump running
- Start with the smaller dose; test again after 4-6 hours before adding more
- Do not exceed 0.6 pH units of reduction in a single addition
- Target range: 7.4-7.6
Example: A 15,000-gallon pool at pH 7.9 needs to drop 0.4 to reach 7.5. Add 30 oz of muriatic acid with pump running. Test again after 4-6 hours.
Muriatic acid dosing for total alkalinity reduction
Critical difference: for TA reduction, add with the pump OFF.
| Pool Size | Lower TA 10 ppm | Lower TA 20 ppm | Lower TA 30 ppm |
|---|---|---|---|
| 10,000 gal | 1 qt (32 oz) | 2 qt (64 oz) | 3 qt (96 oz) |
| 15,000 gal | 1.5 qt (48 oz) | 3 qt (96 oz) | 4.5 qt (144 oz) |
| 20,000 gal | 2 qt (64 oz) | 4 qt (128 oz) | 6 qt (192 oz) |
| 25,000 gal | 2.5 qt (80 oz) | 5 qt (160 oz) | 7.5 qt (240 oz) |
For TA reduction specifically, the technique changes:
- Turn the pump off
- Pour the measured acid into the deep end of the pool in one concentrated spot
- Let it sit for 1-2 hours without circulation
- Turn the pump back on and run for several hours
- Aerate for 24-48 hours (fountains, waterfalls, or a return jet aimed at the surface) to bring pH back up without raising TA again
- Do not add soda ash to recover pH after this treatment. Soda ash raises TA, which defeats the purpose
Example: A 20,000-gallon pool at 150 ppm TA needs to reach 90 ppm (a 60 ppm reduction). Add 12 qts total, in stages of no more than 20 ppm reduction per day. Expect 3 treatment days.
We recommend tracking against TroubleFreePool’s alkalinity guide{:target=“_blank”} for additional context on staged TA reduction.
Quick safety checklist before adding acid
Per CPO acid safety standards{:target=“_blank”} and CDC hydrochloric acid safety guidance{:target=“_blank”}, these steps are required before handling muriatic acid:
- Gloves: acid-resistant rubber or nitrile (not cotton work gloves)
- Goggles: chemical splash goggles (not standard safety glasses)
- Wind: add on a calm day; acid mist is a respiratory hazard
- Water nearby: have a hose ready for emergency skin or eye flush
- AAA rule: Always Add Acid to water, never the other way around
For the full safety protocol and step-by-step addition procedure, see our muriatic acid for pools guide.
How to calculate your own dose
If your pool size falls between the table values, use this formula:
(Your gallons ÷ 10,000) x standard 10k-gallon dose = your dose
Example: You have a 12,000-gallon pool and need to drop pH by 0.4.
- Standard 10,000-gallon dose for 0.4 decrease: 20 oz
- Your calculation: (12,000 ÷ 10,000) x 20 oz = 24 oz
Dry acid conversion: Sodium bisulfate (dry acid) requires about 1.5x the volume of muriatic acid to achieve the same pH reduction. If you prefer dry acid, multiply the muriatic acid dose by 1.5.
We also recommend reading our pool stabilizer dosing guide once pH and TA are balanced, since stabilizer levels affect how much chlorine you need.
For managing your cyanuric acid pool levels, the same principle of staged additions applies.
If you maintain a hot tub in addition to your pool, see our hot tub chemical balancing guide for separate dosing guidelines for spa-size water volumes.
Read our complete pool chemistry guide for the full water balance picture.
FAQ
How long does muriatic acid take to work in a pool?
For pH reduction with the pump running, muriatic acid takes 2-4 hours to fully equilibrate. We recommend waiting at least 4-6 hours and retesting before adding a second dose. For TA reduction with the pump off, allow 1-2 hours for the acid to work, then run the pump and aerate for 24-48 hours.
How many oz is one quart?
One quart equals 32 fluid ounces. One gallon equals 128 fluid ounces, or 4 quarts. These conversions matter when using the TA reduction table above, which lists doses in quarts.
Can I add muriatic acid to a pool with people in it?
No. Always add acid to an empty pool. Wait at least 30 minutes after adding acid before allowing anyone to swim, and retest pH to confirm it is in the 7.2-7.8 range before swimming.
What concentration of muriatic acid should I use for a pool?
The dosing tables above are based on 31.45% concentration (standard pool-grade muriatic acid). Do not use industrial-strength acid (above 33%). If you use a lower concentration product, you will need proportionally more to achieve the same pH reduction.
What happens if I add too much muriatic acid?
The pH drops below 7.0 and the water becomes corrosive. Equipment, metal fittings, and pool surfaces can be damaged. To recover, add sodium carbonate (soda ash) in small amounts to raise pH back to range. Avoid sodium bicarbonate (baking soda) if TA is already in range, as it raises TA rather than pH.