Soda ash raises the pH of pool water, making it less acidic. It’s one of the most common chemicals pool owners use to keep water balanced, and a small amount goes a long way. If your pool’s pH has dipped below the ideal range of 7.4 to 7.6, soda ash is typically the fastest fix.
How Soda Ash Raises pH
Soda ash is the common name for sodium carbonate. When you dissolve it in pool water, it reacts with the hydrogen ions that make water acidic, effectively neutralizing them and pushing the pH upward. The byproduct of that reaction is bicarbonate, which also raises your pool’s total alkalinity (a measure of the water’s ability to resist pH swings).
What makes soda ash so effective is its concentration. With a pH of about 11.3, soda ash is roughly 1,000 times more basic than baking soda (sodium bicarbonate), which sits at a pH of 8.3. That means a very small dose of soda ash produces a noticeable pH change, while you’d need far more baking soda to accomplish the same shift. This is why pool professionals reach for soda ash when pH is the primary problem and turn to baking soda when the main goal is boosting alkalinity without overshooting pH.
Why Low pH Is a Problem
Water that’s too acidic quietly damages almost everything it touches. Metal components like ladders, handrails, and pump internals start to corrode. Plaster walls develop etching and rough patches. Vinyl liners become brittle and prone to tears or wrinkles. Low pH also dissolves trace metals like copper and iron out of your plumbing and equipment, which then deposit as blue, green, or brown stains on pool surfaces.
Beyond equipment damage, acidic water irritates skin and eyes. Chlorine also behaves differently at low pH: it becomes more aggressive but burns off faster, making sanitation harder to maintain. Keeping pH in the 7.4 to 7.6 range protects both your pool’s hardware and the people swimming in it.
How Much to Add
The dose depends on your pool’s volume and how far the pH has dropped. A widely used guideline for a 10,000-gallon pool: if pH is between 7.2 and 7.4, add about 6 ounces of soda ash. If it’s between 7.0 and 7.2, use about 8 ounces. For pools sitting between 6.6 and 7.0, you’ll need closer to 12 ounces. Pools below 6.6 may need a full pound.
For a 20,000-gallon pool, roughly double those figures. For a 5,000-gallon above-ground pool, cut them in half. The key rule: never add more than 2 pounds per 10,000 gallons in a single treatment. If your pool needs more than that, add the first dose, let the water circulate and retest, then treat again.
How to Add It Properly
Soda ash should always be pre-dissolved before it goes into the pool. Dumping the dry powder directly into the water creates a concentrated pocket of very high pH right where it lands. When that happens, calcium already dissolved in your pool water reacts with the carbonate ions and forms calcium carbonate, a chalky white precipitate. This is the clouding effect that pool owners commonly see after adding soda ash incorrectly.
Here’s the process that avoids that problem:
- Wear safety glasses and gloves. Soda ash is a strong base and irritates skin and eyes.
- Fill a bucket about three-quarters full with pool water. Slowly pour the measured dose of soda ash into the bucket. Keep it under 15 pounds per bucket, as larger amounts are hard to dissolve.
- Stir until completely dissolved. No visible powder should remain. If you see grit or cloudiness in the bucket, keep stirring.
- Pour slowly into the pool. Walk along the pool’s edge, distributing the solution across the water rather than dumping it in one spot. Pouring about half, letting fresh pool water dilute the bucket, stirring again, and pouring the rest helps spread it evenly.
Make sure the pump is running the entire time so the treated water circulates immediately. Wait at least 20 minutes to an hour before swimming, then retest the pH to see if you’ve hit your target.
Soda Ash vs. Baking Soda
Both chemicals raise pH and alkalinity, but they do so in very different proportions. Soda ash has a strong effect on pH and a moderate effect on alkalinity. Baking soda has a strong effect on alkalinity and a mild effect on pH. If your pH is low but alkalinity is already in the ideal range of 80 to 120 ppm, soda ash is the better choice because it corrects pH without pushing alkalinity excessively high. If your alkalinity is low and pH is only slightly off, baking soda makes more sense.
In practice, many pool owners keep both on hand. Test your water first, identify which reading is actually out of range, and choose the chemical that targets it. Using the wrong one can overcorrect one value while barely touching the one you needed to fix.
Dealing With Cloudy Water After Treatment
Even with careful pre-dissolving, you may notice some cloudiness after adding soda ash. This happens because the localized spike in pH converts bicarbonate ions into carbonate ions, which then bond with dissolved calcium to form tiny particles of calcium carbonate suspended in the water. The effect is temporary. As the water circulates and the pH distributes evenly, those particles typically settle or get filtered out within a few hours. Running your pump continuously after treatment speeds this up. If cloudiness persists beyond 24 hours, check your calcium hardness level, as pools with very high calcium are more prone to this reaction.