How much baking soda to add to raise your pool’s total alkalinity into range — the buffer that keeps your pH stable.
Most pools aim for 80–120 ppm total alkalinity. Need to bring it down instead? Use the Muriatic Acid Calculator.
Add this much baking soda
8.4 lb (≈ 134 oz)
to raise alkalinity from 70 to 100 ppm in 20,000 gal
≈ 1.4 lb baking soda per 10 ppm per 10,000 gal → (100 − 70) ppm × 20,000 gal = 8.4 lb (≈ 134 oz)
Sodium bicarbonate adds 1 equivalent of alkalinity per mole; the rise is linear in ppm and pool volume.
Use 100% sodium bicarbonate — pool “alkalinity increaser” and plain baking soda are the same thing. Broadcast it over the deep end with the pump running.
Baking soda nudges pH up a little as well. Re-test pH after a few hours and adjust if needed.
Total alkalinity (TA) is the water’s buffering capacity — its resistance to pH change. When alkalinity is in range, pH stays put; when it’s too low, pH bounces around at the smallest provocation and the water turns aggressive and corrosive. The fix for low alkalinity is baking soda (sodium bicarbonate), the same compound sold at a markup as “alkalinity increaser.”
Baking soda raises alkalinity strongly and pH only slightly, which is exactly what you want when TA is low but pH is okay. If your pH is the low one and alkalinity is fine, reach for soda ash instead. And if alkalinity is too high, baking soda can’t help — that’s a job for acid.
A 20,000-gallon pool at 70 ppm alkalinity, targeting 100 ppm:
At about 1.4 lb per 10 ppm per 10,000 gallons, a 30 ppm rise across 20,000 gallons works out to roughly 8.4 lb of baking soda. Broadcast it over the deep end with the pump running, then re-test alkalinity and pH after a few hours — the pH will have crept up a little along with the alkalinity.
About 1.4 lb of baking soda per 10,000 gallons raises total alkalinity by roughly 10 ppm. So a 20,000-gallon pool going from 70 to 100 ppm (a 30 ppm bump) needs about 8.4 lb. Enter your pool size and levels above for the exact amount — and add it in stages if it’s a big change.
Yes. “Alkalinity increaser” or “alkalinity up” sold for pools is sodium bicarbonate — the same compound as ordinary baking soda. Plain Arm & Hammer (or any pure sodium bicarbonate) works identically and is usually far cheaper by the pound. Just make sure it’s 100% sodium bicarbonate with no additives.
A little. Baking soda mainly raises alkalinity, but it nudges pH upward toward about 8.0–8.3. If your pH is already high, that’s worth watching. To raise alkalinity with minimal pH change, add baking soda; to raise pH with minimal alkalinity change, use soda ash (sodium carbonate) instead.
Use baking soda (sodium bicarbonate) when total alkalinity is low and pH is okay — it raises alkalinity strongly and pH only slightly. Use soda ash (sodium carbonate, “pH up”) when pH is low but alkalinity is fine — it raises pH strongly. They’re different chemicals for different problems, though both push in the “up” direction.
Most pools run best with total alkalinity between 80 and 120 ppm (often 100 ppm is the sweet spot; some salt and plaster pools aim a little lower). Alkalinity is the buffer that keeps pH stable — too low and pH bounces around and water turns corrosive; too high and pH drifts up and you fight scale and cloudiness.
Baking soda only raises alkalinity. To lower it you add acid — muriatic acid or dry acid — which drops alkalinity (and pH) together; then you aerate to bring pH back up while alkalinity stays down. Use the Muriatic Acid Calculator for the exact acid dose.
Broadcast it across the deep end with the pump running, give it about 20–30 minutes to circulate and dissolve, then you’re generally fine to swim once it’s mixed in. Re-test alkalinity (and pH) after a few hours, since baking soda nudges pH up a touch.
It’s linear: each 10 ppm rise in alkalinity per 10,000 gallons takes a fixed amount of sodium bicarbonate (about 1.4 lb). The tool scales that by your pool volume and the size of the increase you want, then expresses it in pounds (and ounces for small amounts).
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