Pool Alkalinity Calculator
Total alkalinity (TA) keeps pH steady. Enter your reading and target to get how much baking soda to add, or how much acid to lower it.
Quick answer: To raise total alkalinity 10 ppm in a 10,000-gallon pool, add about 22 oz of baking soda. Lowering it 10 ppm takes about 26 fl oz (3.2 cups) of 31.45% muriatic acid, added in stages.
Checked against 6 published sources (see them). Updated October 2026.
- Raises alkalinity by
- 30 ppm
- Next step
- Retest in 6 hours
- Spread it over the surface with the pump running. Add big amounts in two or three goes.
Baking soda to raise alkalinity 10 ppm
| Pool size | Baking soda |
|---|---|
| 5,000 gal | 11 oz |
| 10,000 gal | 22 oz |
| 15,000 gal | 2 lb 2 oz |
| 20,000 gal | 2 lb 13 oz |
| 25,000 gal | 3 lb 8 oz |
| 30,000 gal | 4 lb 3 oz |
How it works
Baking soda: about 1.4 lb raises alkalinity 10 ppm in 10,000 gallons (Indiana Department of Health and Wojtowicz's published formula; PHTA rounds to 1.5 lb).
Acid: about 26 fl oz of 31.45% muriatic acid, or about 2.1 lb of dry acid, lowers alkalinity 10 ppm in 10,000 gallons (Indiana, PHTA and Wojtowicz agree).
Lowering alkalinity is a process. Acid lowers pH and alkalinity together, then aeration (pointing returns up, running waterfalls or jets) raises pH back without raising alkalinity. Repeat until alkalinity reaches the target.
Tips
- Lower alkalinity in steps: add acid until pH is about 7.0–7.2, aerate until pH is back to 7.4–7.6, retest, repeat.
- Don't add pH up (soda ash) while you're lowering alkalinity.
- Raising alkalinity with baking soda barely moves pH, so it's safe to do first.
Sources
We checked the math on this page against:
- Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool
- Pool & Hot Tub Alliance fact sheet: Alkalinity
- Wojtowicz, "Swimming Pool and Spa Water Chemical Adjustments," Journal of the Swimming Pool and Spa Industry (2004)
- Lucas County (Ohio) Health Department: Pool Chemistry Adjustments
- AQUA Magazine: Using air and acid to get pH and alkalinity right
- Trouble Free Pool: Lowering total alkalinity
Frequently asked questions
How much baking soda raises alkalinity in a 15,000-gallon pool?
About 2 lb 2 oz raises it 10 ppm. To go from 60 to 90 ppm takes about 6 lb 5 oz.
What should total alkalinity be?
The CDC's Model Aquatic Health Code allows 60–180 ppm. PHTA suggests 80–100 ppm for liquid chlorine and salt pools and 100–120 ppm with dichlor or trichlor.
Can I lower alkalinity in one go?
Not well. Dumping all the acid at once crashes pH. Use the acid-then-aerate steps and retest between rounds.