Guide
How to raise alkalinity in a pool
Raise total alkalinity with baking soda, 1.4 lb per 10,000 gallons for each 10 ppm, with the target for your pool, a dose table in pounds and grams, and how to lower it with acid and aeration.
Updated · 3 min read
To raise total alkalinity (TA), add baking soda (sodium bicarbonate), separately, with the pump running. 1.4 lb per 10,000 US gallons raises TA by 10 ppm, or 168 g per 10,000 litres. To lower TA, you do the opposite in two moves: acid to bring pH down to 7.2, then aeration to let pH climb back, repeated over a few days.
The target for your pool
| Pool | TA range (ppm) | Aim for |
|---|---|---|
| Liquid chlorine or salt | 60 to 80 | 70 |
| Trichlor tablets | 80 to 120 | 100 |
| Hot tub | 50 to 90 | 60 |
| Biguanide (non-chlorine) | 80 to 150 | 100 |
If you have read "80 to 120" elsewhere, that range assumes trichlor tablets, which are acidic and eat alkalinity. With liquid chlorine or a salt cell, 60 to 80 holds pH steadier with less acid, and TA can safely sit as low as 50.
Baking soda doses
| Raise TA by | Per 10,000 US gal | Per 10,000 litres |
|---|---|---|
| 10 ppm | 1.4 lb | 168 g |
| 20 ppm | 2.8 lb | 336 g |
| 30 ppm | 4.2 lb | 504 g |
| 40 ppm | 5.6 lb | 671 g |
| 50 ppm | 7.0 lb | 839 g |
Baking soda barely moves pH: raising TA by 10 ppm nudges pH up about 0.02. In Australia it's sold as "buffer"; pool "alkalinity increaser" is the same chemical.
How to raise alkalinity, step by step
- Test TA and pH. Fix TA first, because TA is what holds pH steady.
- Work out the dose. Subtract your TA from the goal and scale the table to your pool.
- Add the baking soda separately, with the pump running. Sprinkle it over the deep end, or pre-dissolve it in a bucket of pool water, and brush any that settles.
- Wait an hour, then retest TA and pH. Add more only if TA is still short of the goal.
- Adjust pH last. Wait 30 minutes after any product before adding the next, and never mix products.
Lowering alkalinity: acid, then air
There is no product that lowers TA on its own. Instead:
- Add acid to bring pH down to 7.2 (or as low as 7.0), separately, with the pump running.
- Aerate: point the return jets up at the surface and run waterfalls or spa jets until pH climbs back to about 7.6. Aeration raises pH without raising TA.
- Repeat once a day, testing TA and pH before each round, until TA reaches its range.
Allow at least 30 minutes after adding acid, with the pump running, before testing pH again. For scale: in 10,000 gallons, each 25.6 fl oz of 31.45% muriatic acid (or 34.4 oz of dry acid) removes about 10 ppm of TA; per 10,000 litres, 200 mL of muriatic or 257 g of dry acid. The pH guide has the acid doses by pH.
If pH is low and TA is high at the same time, skip the acid: aerate alone until pH is near 7.6.
Questions people ask
Can I use baking soda from the grocery store?
Yes. It's the same chemical, sodium bicarbonate, as pool "alkalinity increaser". Dose it by weight.
Will raising TA raise my pH a lot?
No. Baking soda nudges pH up only slightly. If pH is already high, lower TA with acid and aeration instead of adding more baking soda.
My TA is high and my pH is low. What now?
Aeration is the fix: it raises pH without touching TA. Skip chemicals until pH is back near 7.6, then lower TA if it is still above range.
What TA should a salt pool have?
60 to 80 ppm, aiming for 70. Salt cells push pH up as they run, and TA in this range keeps that easier to manage.
How fast can I lower TA?
About one acid-and-aeration round a day. Test before each round and stop when you reach the range; TA can safely go as low as 50 ppm.
For a plan in the right order, TA before pH before chlorine, enter your readings in the water check.