How to lower alkalinity in a pool The short answer To lower alkalinity in a pool, add muriatic acid or dry acid until pH is about 7.0–7.2, then aerate the water — point the return jets up, run fountains or a waterfall — to raise pH again without raising alkalinity. Repeat until alkalinity is 60–100 ppm (60–80 in a salt pool). The calculator below gives the acid dose for your pool.
How much acid your pool needs Alkalinity now
Total alkalinity holds pH steady, so it does not swing up and down.
Alkalinity you want
Good range: 60–100 ppm.
Using baking soda.
Type the size and your alkalinity reading.
Step by step Work out the acid dose with the calculator on this page.
With the pump running and gloves and eye protection on, pour the acid slowly in front of a return jet.
Test pH after an hour. Stop adding acid if pH is under 7.0.
Aerate for a day or two until pH is back at 7.4–7.6, then repeat until alkalinity is in range.
The product label always wins — if it says something different, follow the label.
Why it happens High alkalinity usually comes from the fill water, or from adding baking soda or soda ash.
It makes pH climb, and together they can cloud the water and scale surfaces and heaters.
Questions Can I lower alkalinity without lowering pH? No chemical lowers alkalinity alone. Acid lowers both; aeration then raises pH back up without touching alkalinity — that is the whole trick.
How long does it take? Usually a few days of acid-then-aerate rounds. Small steps are safer than one big dose.
Muriatic acid or dry acid? Both work the same way. Muriatic acid is cheaper; dry acid is easier to store and handle.
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