How to Lower Total Alkalinity in a Pool (Muriatic Acid Amounts)
Muriatic acid lowers total alkalinity (TA), and it also lowers pH. The amount depends on pool volume and the size of the TA reduction. This calculator estimates 31.45% muriatic acid from the chemistry shown in the pool chemical calculator; treat the amount as an estimate and retest before adding more.
Approximate muriatic acid amounts
For 31.45% muriatic acid, the pool chemical calculator's formula gives about 25.6 fluid ounces per 10,000 gallons for each 10 ppm decrease in TA. The Indiana Department of Health dosing sheet rounds this to 26 fluid ounces.
| Pool volume | Approx. acid for −10 ppm TA |
|---|---|
| 5,000 gallons | 12.8 fl oz |
| 10,000 gallons | 25.6 fl oz |
| 15,000 gallons | 38.4 fl oz |
| 20,000 gallons | 51.2 fl oz |
| 30,000 gallons | 76.8 fl oz |
Example: for a 10,000-gallon pool going from 100 to 80 ppm, the estimate is two 10-ppm steps, or about 51.2 fl oz. The calculator uses the volume and readings you enter. Pool water can respond differently, so this is not a guaranteed pH or TA result.
Add acid carefully and retest
- Verify pool volume and test the water before calculating.
- Read the acid label and wear the protective equipment it specifies.
- With the pump running, add acid carefully to pool water according to the label. Never pour water into acid. Keep swimmers out while adding chemicals.
- For a large estimate, add only a portion first. Allow circulation, then retest both TA and pH before deciding whether to add more.
- Follow the product label and pool-maker instructions; the label is the final word.
Virginia Department of Health advises following chemical labels, adding chemicals to water and never water to chemicals, not adding chemicals while the pool is in use, storing liquid products below dry products in their original containers, and using the protective gear listed on the label.
Sources
- Formula and arithmetic: Pool Chemical Calculator, cross-checked against the Indiana Department of Health chemical adjustment sheet.
- Virginia Department of Health, Pool Chemical Safety.