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Pool Alkalinity Calculator

How much baking soda to raise total alkalinity, or muriatic acid to lower it

Reviewed by Skimmer Editorial Team. Updated .

How these numbers are worked out, and the sources behind them: see our methodology.

Pool alkalinity formula

lb of baking soda = gallons / 10,000 x TA rise / 10 x 1.5

To lower TA, use about 32 fl oz of 31.45% muriatic acid (or 64 fl oz of 14.5%) per 10,000 gallons per 10 ppm, or about 2 lb of dry acid. Worked example: a 15,000 gallon pool from 60 to 100 ppm needs 15,000 / 10,000 x 40 / 10 x 1.5 = 9 lb of baking soda, added in two rounds of 4.5 lb.

Baking soda calculator for pools: dosing chart

Pounds of baking soda to raise total alkalinity
Pool size+10 ppm+20 ppm+30 ppm+40 ppm+50 ppm
5,000 gal0.8 lb1.5 lb2.3 lb3.0 lb3.8 lb
10,000 gal1.5 lb3.0 lb4.5 lb6.0 lb7.5 lb
15,000 gal2.3 lb4.5 lb6.8 lb9.0 lb11.3 lb
20,000 gal3.0 lb6.0 lb9.0 lb12.0 lb15.0 lb
25,000 gal3.8 lb7.5 lb11.3 lb15.0 lb18.8 lb
30,000 gal4.5 lb9.0 lb13.5 lb18.0 lb22.5 lb

Muriatic acid chart to lower alkalinity

Fl oz of muriatic acid (31.45% / 14.5%)
Pool size-10 ppm-20 ppm-30 ppm-40 ppm
5,000 gal16 / 3532 / 6948 / 10464 / 139
10,000 gal32 / 6964 / 13996 / 208128 / 278
15,000 gal48 / 10496 / 208144 / 312192 / 416
20,000 gal64 / 139128 / 278192 / 416256 / 555
25,000 gal80 / 174160 / 347240 / 521320 / 694
30,000 gal96 / 208192 / 416288 / 625384 / 833

Ideal total alkalinity by pool type

  • Plaster, gunite or pebble with chlorine: 90 to 120 ppm.
  • Vinyl or fiberglass with chlorine: 80 to 100 ppm.
  • Saltwater, any surface: 60 to 80 ppm. Salt cells raise pH as they make chlorine, and lower TA slows that climb. See the salt calculator.

TA vs pH: which to adjust first

Fix alkalinity first. TA is the buffer that holds pH, so pH won't stay put until TA is in range. The exception is very high pH (above 8.0), which makes chlorine weak: bring it down to about 7.8 with acid first, then work on TA. Fine-tune pH with the pool pH calculator, and check calcium with the calcium hardness calculator.

Lowering TA with the aeration method

  1. Turn the pump off so the water is still.
  2. Pour the acid slowly into one spot in the deep end, away from skimmers and returns.
  3. Wait a few hours, then turn the pump back on.
  4. Aerate: point returns up, run waterfalls or a fountain, or use an air compressor. pH rises, TA doesn't.
  5. Retest the next day and repeat until TA reaches target. It usually takes several rounds.

Step-by-step guides: how to raise total alkalinity and how to lower total alkalinity.

How to use this calculator
  1. 1
    Enter your pool volume

    Don't know it? Use the inline estimate or the Pool Volume Calculator.

  2. 2
    Choose raise or lower TA

    Enter your current reading and pick a target: 100 ppm for chlorine pools, 80 ppm for salt pools.

  3. 3
    Pick your product

    Baking soda or soda ash to raise TA. Muriatic acid or dry acid, with the aeration method, to lower it.

  4. 4
    Dose in rounds

    Raise up to about 20 ppm per round and lower about 10 ppm per round, circulating 6 hours between.

  5. 5
    Retest

    Retest TA and pH after each round before adding more.

More free tools
Pool Chemical Calculator (all-in-one)

Adjusting more than one number? Get every dose from one test, in order.

Pool Volume Calculator

Don't know your pool's gallons yet? Start here.

Pool pH Calculator

Alkalinity is the buffer that keeps pH from bouncing around.

LSI / Water Balance Calculator

See how alkalinity, calcium, pH and temperature balance together.

Calcium Hardness Calculator

The other half of water balance.

Salt Calculator

Salt pools drift up in pH and TA.

More pool calculators →
Frequently asked

Questions about total alkalinity

How much baking soda does my pool need?
About 1.5 lb of baking soda per 10,000 gallons raises total alkalinity by 10 ppm. Enter your gallons and current and target TA above for the exact dose.
How many pounds of baking soda for 10,000 gallons?
1.5 lb per 10 ppm. Going from 60 to 100 ppm in 10,000 gallons takes 6 lb, best added in two rounds.
Why does lowering TA require a special procedure, not just a dose?
Acid lowers pH right away, but TA only drops when carbon dioxide leaves the water. Pour the acid into one deep spot with the pump off, wait a few hours, then aerate to bring pH back up. Repeat until TA reaches target.
Will raising total alkalinity also raise my pH?
Slightly with baking soda, a lot with soda ash. Retest pH after each round before deciding whether you need acid.
Can I use soda ash instead of baking soda?
Yes, but soda ash raises pH much more. Use it only when pH and TA are both low. If pH is already in range, use baking soda.
What's the ideal total alkalinity range?
80 to 120 ppm for most chlorine pools, with 100 a good target. Salt pools do better at 60 to 80 ppm because the cell pushes pH up. Plaster pools sit at the top of the range, vinyl and fiberglass the lower end.
How long after adding baking soda can I swim?
Once it has dissolved and circulated, usually about an hour. Baking soda is the same chemical you cook with, so it's safe to swim once the water is clear.
How long after adding should I retest?
About 6 hours with the pump running for baking soda. For acid and aeration, retest the next day.
Why did my TA drop after rain?
Rain is soft and slightly acidic, so heavy rain dilutes and lowers alkalinity. Retest after a big storm.
Does shock affect alkalinity?
A little. Liquid chlorine and cal-hypo raise pH but barely move TA. Dichlor and trichlor are acidic and slowly lower TA over the season.