How to Raise pH in a Pool
When your test shows pH at 7.0 or below, soda ash (sodium carbonate) is the standard fix: about 6 ounces raises pH by 0.2 points in 10,000 gallons. This guide walks through the math, why baking soda is the wrong tool for this job, and how aeration can raise pH without adding any chemical at all.
To raise pool pH, add soda ash at roughly 6 ounces per 0.2 pH rise per 10,000 gallons. A 20,000 gallon pool at pH 6.9 needs about 30 ounces (1.9 pounds) to reach 7.4. Dissolve it in a bucket and pour around the pool edges with the pump running. Soda ash also raises alkalinity, so retest both.
The short answer: soda ash, dosed by the math
Low pH (below 7.2) makes chlorine harsh, corrodes metal equipment and heaters, etches plaster, and irritates eyes and skin. The fix is soda ash, also called sodium carbonate or pH Up. The rule of thumb our calculator uses: about 6 ounces of soda ash per 0.2 pH rise per 10,000 gallons. Soda ash also raises total alkalinity, so always retest alkalinity a few hours after dosing.
Aeration is the chemical-free alternative. Anything that drives carbon dioxide out of the water raises pH: run waterfalls and fountains, point return jets at the surface, or add a cheap aerator nozzle. Aeration raises pH without touching alkalinity, which makes it the best choice when alkalinity is already fine and only pH is low.
Worked example 1: 20,000 gallons, pH 6.9 up to 7.4
The rise is 0.5 pH points (7.4 minus 6.9).
(0.5 / 0.2) x 6 oz x (20,000 / 10,000) = 30 ounces, or about 1.9 pounds.
Dissolve the 30 ounces in a bucket of pool water and pour it around the pool edges with the pump running. Wait 3 to 4 hours, then retest pH and alkalinity. If pH still sits under 7.2, repeat with the same formula rather than guessing.
Worked example 2: 10,000 gallons, pH 7.0 up to 7.4
Smaller move, smaller dose: the rise is 0.4 pH points.
(0.4 / 0.2) x 6 oz = 12 ounces, or about 3/4 pound.
Same drill: dissolve, pour around the edges, circulate, retest. This is a dose you can eyeball against a kitchen scale, no need for a lab balance.
Baking soda is not a pH fixer
The most common mistake is grabbing baking soda for low pH. Baking soda (sodium bicarbonate) is an alkalinity tool: 1.5 pounds per 10,000 gallons raises total alkalinity by 10 ppm but barely moves pH. Using it to chase pH just inflates alkalinity, and high alkalinity then drags pH upward uncontrollably. The rule is simple: baking soda for low alkalinity, soda ash for low pH, and never substitute one for the other.
Why pH drops in the first place
The usual causes are easy to spot. Rain is slightly acidic and dilutes the water. Trichlor tablets and dichlor granules are acidic sanitizers that steadily pull pH down, which is why tablet-chlorinated pools need soda ash more often. Heavy swimmer loads and organic debris also push pH down. If you are adding soda ash every week, check what is driving it: switching from trichlor to liquid chlorine (which is nearly pH-neutral over time) often ends the cycle.
How to add soda ash safely
Soda ash is a base, so wear gloves and eye protection like any pool chemical. Dissolve the measured amount in a bucket of pool water first, then pour the solution around the pool perimeter with the pump running. Never dump dry granules directly onto the pool floor; concentrated piles can bleach vinyl liners and leave white residue on plaster. Keep the pump running for at least 30 minutes, and retest pH and alkalinity after a few hours before swimming.
Skip the arithmetic
Rather than doing the soda ash math by hand, enter your pH now and your target into our free pool chemical calculator and get the exact dose for your pool's volume.
Raising pool pH: common questions
Can I use baking soda to raise pH in my pool?
Baking soda is the wrong tool for low pH. It mainly raises total alkalinity: 1.5 pounds per 10,000 gallons adds 10 ppm of alkalinity but barely moves pH. Use soda ash (sodium carbonate) for low pH instead, about 6 ounces per 0.2 pH rise per 10,000 gallons.
How long does soda ash take to raise pH?
A few hours with the pump running. Dissolve it, add it, circulate for at least 30 minutes, and retest pH and alkalinity after 3 to 4 hours. Add a second dose from the formula if pH still reads below 7.2.
Why is my pool pH always low?
Acidic sanitizers are the usual cause: trichlor tablets and dichlor granules steadily pull pH down. Rain, heavy use, and organic debris also lower it. If you dose soda ash constantly, switching to liquid chlorine often breaks the cycle.
How much soda ash raises pH from 7.0 to 7.4 in a 10,000 gallon pool?
About 12 ounces, roughly 3/4 pound. The math is (0.4 / 0.2) times 6 ounces. Dissolve it in a bucket and pour around the pool edges with the pump running, then retest after a few hours.
Will raising pH raise my alkalinity too?
Yes, if you use soda ash: it raises both. If alkalinity is already in range and only pH is low, use aeration instead (fountains, waterfalls, jets at the surface), which raises pH without adding alkalinity.