Pool Alkalinity Calculator

The ideal total alkalinity (TA) range is 80–120 ppm for most pools. The APSP and most pool professionals recommend 80–120 ppm as the target range. TA below 80 ppm causes pH to swing unpredictably (pH bounce), while TA above 120 ppm makes it difficult to adjust pH and can contribute to scale formation.

Add sodium bicarbonate (baking soda) to raise total alkalinity. Approximately 1.5 lbs of baking soda raises TA by 10 ppm in a 10,000-gallon pool. Pre-dissolve in a bucket of water, then pour around the pool perimeter with the pump running. Retest after 6 hours. Dose in increments; raise no more than 20–30 ppm at a time.

Acid lowers alkalinity and pH together — there is no dose that separates them. The method that works is to lower pH in small steps with acid, then aerate: running a spa jet, fountain or an upward-pointed return drives off carbon dioxide and brings pH back up WITHOUT restoring the alkalinity you removed. Repeat the pair until alkalinity reaches target. Add acid with the pump running, spread over a wide area of deep water. Do NOT use the old "column method" of pouring concentrated acid into one spot with the pump off: controlled testing found it gives the same result as normal distribution once the water circulates, while creating a pocket of pH below 2.5 that etches plaster and attacks metal.

Total alkalinity acts as a pH buffer. It resists rapid pH swings caused by rain, bather load, or chemical additions. Without adequate TA, pH becomes unstable ("pH bounce"), which affects chlorine effectiveness and swimmer comfort. TA also plays a role in the Langelier Saturation Index (LSI), which determines whether water is scale-forming or corrosive.

Baking soda (sodium bicarbonate) primarily raises total alkalinity with a modest effect on pH. It raises pH by roughly 0.1–0.2 units per treatment at typical doses. Soda ash (sodium carbonate) is the better choice if you want to raise pH significantly. Use baking soda when TA is low and pH is already near the target range.