Total alkalinity calculator
Updated:
Total alkalinity is pH’s shock absorber. Enter your current and target alkalinity and pool volume to get the exact amount of baking soda to add (or acid to lower it).
How much baking soda to raise alkalinity?
About 1.4 lb of baking soda (sodium bicarbonate) per 10,000 gallons raises total alkalinity by about 10 ppm. That is the same figure the MAHC Annex gives, and the calculator scales it to your volume and target. Baking soda nudges pH up only slightly, so it is the right tool when alkalinity is the low reading.
Raise alkalinity before pH
Alkalinity stabilizes pH, so set it first. If alkalinity is too low, pH bounces around unpredictably; too high and pH drifts upward and water can cloud. Bring TA into range, then fine-tune pH.
Lowering alkalinity
There is no separate alkalinity reducer. You lower TA with acid, which lowers pH too, then aerate to bring pH back up. By stoichiometry, 10 ppm of alkalinity in 10,000 gallons takes about 26 fl oz (0.8 quart) of 31.45% muriatic acid. The MAHC Annex quotes 1.3 quarts of muriatic acid for the same job without stating the acid’s strength, so use the calculator’s figure for full-strength acid and re-test before adding more.
How the dose is calculated
One constant for each direction.
Raising with baking soda
grams = 0.0063589 × (target TA − current TA) × gallons
Alkalinity is reported as calcium carbonate, 50.04 g per equivalent. Baking soda is 84.01 g per equivalent, so each ppm needs about 1.68 mg per liter, or 6.36 mg per gallon. For 10 ppm in 10,000 gallons that is 636 g, or 1.40 lb.
Lowering with acid
liters of 31.45% acid = (TA drop ÷ 50,044) × pool liters ÷ 10.0
Each equivalent of acid removes one equivalent of alkalinity. For 10 ppm in 10,000 gallons that is 0.76 L, about 26 fl oz.
Ideal ranges
| Level | Target | Notes |
|---|---|---|
| Required range (MAHC) | 60–180 ppm | MAHC 5.7.4.4.1 |
| Liquid chlorine or salt pool | 60–90 ppm | TFP; the low end slows pH rise |
| Equipment makers | 80–120 ppm | Hayward AquaRite and Pentair IntelliChlor manuals; the range the app uses |
Frequently asked questions
Baking soda or soda ash?
Baking soda (sodium bicarbonate) raises alkalinity with minimal pH change. Soda ash (sodium carbonate) is for raising pH and raises alkalinity as a side effect.
Will baking soda raise my pH?
Only slightly. It mainly moves alkalinity, which is exactly what you want when TA is low.
How much acid lowers alkalinity by 10 ppm?
About 26 fl oz of 31.45% muriatic acid per 10,000 gallons. Add it to the deep end with the pump running, then aerate to recover pH.
Sources
- CDC, Model Aquatic Health Code, 5th edition (2024), Code Language. Section 5.7.4.4.1: total alkalinity 60–180 ppm
- CDC, Model Aquatic Health Code, 5th edition (2024), Annex. Section 5.7.4.4.1: 1.4 lb of baking soda per 10,000 gallons raises alkalinity about 10 ppm
- Trouble Free Pool, Pool Chemical Levels: Pool Industry vs TFP (December 21, 2025). 60–90 ppm for liquid chlorine and salt pools
- Hayward, AquaRite 900 Series Electronic Chlorine Generator manual (092623 Rev D). Alkalinity 80–120 ppm
- Pentair, IntelliChlor IC15/IC20/IC40/IC60 Installation and User’s Guide (P/N 520589 Rev. R, 2023). Total alkalinity 80–120 ppm
Related calculators & guides
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