How to use this pool alkalinity calculator
- Enter your pool volume.
- Test total alkalinity.
- Enter the target (60–90 ppm for most chlorine pools; follow your salt cell or plaster guidance).
- Add chemicals in portions and retest.
Example
Raising a 20,000 gallon pool from 60 to 90 ppm of total alkalinity takes 8.41 lb of baking soda (sodium bicarbonate).
What to know before you buy
What total alkalinity does
Total alkalinity measures the water's ability to resist pH changes. When TA is too low, pH swings quickly and can corrode surfaces; when it is too high, pH keeps drifting up and scale forms. Adjust TA first, then fine-tune pH.
Recommended ranges
Pools using liquid chlorine or a salt generator often do best with TA around 60–80 ppm, which reduces pH rise. Pools using trichlor tablets, which are acidic, usually need 80–120 ppm. Follow your pool surface and equipment manufacturer's guidance.
Baking soda to raise TA by 10 ppm
| Pool volume | Baking soda to add |
|---|---|
| 5,000 gal | 0.7 lb |
| 10,000 gal | 1.4 lb |
| 15,000 gal | 2.1 lb |
| 20,000 gal | 2.8 lb |
| 30,000 gal | 4.21 lb |
Formula
Baking soda (mg) = liters × ppm × 84 ÷ 50 (TA measured as CaCO₃). Muriatic acid: each 50 mg/L of TA needs 36.5 mg/L of HCl; 31.45% acid has a density of about 1.16 g/mL.
Tips from the pros
- Adjust alkalinity before pH: TA acts as a buffer that keeps pH stable.
- Household baking soda is the same product as pool "alkalinity increaser" and much cheaper.
- To lower TA, add acid to lower pH to about 7.0–7.2, then aerate to raise pH without raising TA; repeat as needed.
Common mistakes to avoid
- Using soda ash (sodium carbonate) to raise TA: it raises pH a lot more than baking soda.
- Adding large doses at once instead of in portions with retesting.
Frequently asked questions
How much baking soda raises alkalinity 10 ppm?
About 1.4 lb per 10,000 gallons.
What is the ideal pool alkalinity?
Typically 60–90 ppm for pools using liquid chlorine or salt, and 80–120 ppm for pools using trichlor tablets.
How much baking soda to raise alkalinity in a 15,000 gallon pool?
About 2.1 lb raises TA by 10 ppm in 15,000 gallons.
Does baking soda raise pH?
Only slightly. It mainly raises total alkalinity; use soda ash or aeration to raise pH.