Pool alkalinity calculator
How much baking soda to bring total alkalinity up to your target, and the honest answer for bringing it down: no bottle does it, but acid and aeration do.
- Raise free chlorine 10 ppm
- ~107 fl oz liquid (12.5%) (3.3 qt; 3.2 L), ~19 oz cal-hypo (70%) (539 g), or ~22 oz dichlor (62%) (624 g)
- Raise alkalinity (TA) 10 ppm
- ~1.5 lb baking soda (680 g)
- Raise calcium (CH) 10 ppm
- ~1.2 lb calcium chloride (77% flake) (544 g)
- Raise stabilizer (CYA) 10 ppm
- ~13 oz cyanuric acid (369 g)
- Lower pH 8.0 → 7.6 (at TA 100)
- ~10 fl oz muriatic acid (1.3 cups; 296 mL), or ~0.9 lb dry acid (408 g)
Ballpark for a 10,000-gallon pool. Enter your size and levels below for your exact dose.
Example numbers are filled in so you can see an answer. Type your own over them.
Don't know your gallons? Work it out here →
Exact geometry at 7.48 gal/ft³. Kidney shapes, diving hoppers and salt/turnover figures live in the full Pool Volume Calculator.
Baking soda to raise alkalinity
| Raise by | 5,000 gal (18,927 L) | 10,000 gal (37,854 L) | 15,000 gal (56,781 L) | 20,000 gal (75,708 L) | 25,000 gal (94,635 L) | 30,000 gal (113,562 L) |
|---|---|---|---|---|---|---|
| 10 ppm | 12.0 oz (340 g) | 1.5 lb (680 g) | 2.3 lb (1.0 kg) | 3.0 lb (1.4 kg) | 3.8 lb (1.7 kg) | 4.5 lb (2.0 kg) |
| 20 ppm | 1.5 lb (680 g) | 3.0 lb (1.4 kg) | 4.5 lb (2.0 kg) | 6.0 lb (2.7 kg) | 7.5 lb (3.4 kg) | 9.0 lb (4.1 kg) |
| 30 ppm | 2.3 lb (1.0 kg) | 4.5 lb (2.0 kg) | 6.8 lb (3.1 kg) | 9.0 lb (4.1 kg) | 11.3 lb (5.1 kg) | 13.5 lb (6.1 kg) |
Lowering alkalinity: acid, then air
Acid lowers pH and alkalinity together. Aeration raises pH without adding alkalinity back, because it only drives carbon dioxide out of the water. Alternate the two and alkalinity comes down while pH ends where you want it:
- Add acid to bring pH to about 7.2. The pH calculator gives the amount.
- Aerate: point returns at the surface, run a waterfall, spillover or fountain.
- When pH is back near 7.6–7.8, retest alkalinity and repeat if it is still high.
Why bother? Carbon dioxide leaves the water faster at high alkalinity, and that is what pushes pH up. Bringing alkalinity toward 60–80 means less acid every week. More in pool pH explained, and the one-big-dose method debunked in the acid slug myth.
Target: Trouble Free Pool's ideal levels (TA 60–80). Dose: 1.5 lb (680 g) of baking soda per 10 ppm per 10,000 gallons (Trouble Free Pool's figure). Estimates; retest after a few hours.
FAQ
How much baking soda raises alkalinity?
About 1.5 lb (680 g) of baking soda raises total alkalinity 10 ppm in 10,000 gallons. The calculator scales it to your pool and your target.
What should total alkalinity be in a pool?
Trouble Free Pool's ideal is 60–80 ppm for every pool type, salt included. The 80–120 you see on many labels and salt-cell manuals is not dangerous, but higher alkalinity makes pH climb faster, which means more acid.
How do I lower total alkalinity?
There is no one-bottle fix. Add acid to bring pH down to about 7.2, then aerate (returns up, a waterfall or fountain) to raise pH back without adding alkalinity, and repeat. Each round takes alkalinity down a little. It is slow, and it works.
Does baking soda raise pH?
A little. Baking soda mostly raises alkalinity and nudges pH up slightly, which is why it is the right product when alkalinity is low. To raise pH on its own, aerate or use borax.
Is pool store "alkalinity up" different from baking soda?
Usually not: the active ingredient is the same sodium bicarbonate. Compare price per pound, not the label.