High pH is one of the most common pool chemistry problems — and one of the most misunderstood. When your pH climbs above 7.6, your chlorine starts losing its effectiveness fast. By the time you hit 8.0, your chlorine is barely doing anything at all, even if the reading looks fine.
The good news is that lowering pH is straightforward once you know what you're doing. Here's exactly how to do it.
Pool water should be between 7.2 and 7.6, with 7.4 being the sweet spot. Below 7.2 and the water becomes corrosive — it'll irritate eyes and eat away at equipment. Above 7.6 and chlorine efficiency drops sharply.
You have two options: muriatic acid (liquid) or dry acid (sodium bisulfate). Both work well — muriatic acid is cheaper and faster acting, dry acid is safer to handle and store.
These are approximate amounts to drop pH by about 0.2 points. Always add less than you think you need and retest — you can always add more, you can't take it out.
| Pool Size | pH 7.8 → 7.4 | pH 8.0 → 7.4 |
|---|---|---|
| 10,000 gal | 6 oz | 12 oz |
| 15,000 gal | 9 oz | 18 oz |
| 20,000 gal | 12 oz | 24 oz |
| 25,000 gal | 15 oz | 30 oz |
| 30,000 gal | 18 oz | 36 oz |
⚠️ Safety first: Always add acid to water, never water to acid. Wear gloves and eye protection. Add it near a return jet with the pump running to distribute it quickly.
Dry acid (sodium bisulfate) is about 20% less potent per ounce than muriatic acid. Use roughly 1.25x the muriatic acid amount as a starting point, then retest after an hour.
💡 Check alkalinity first. If your alkalinity is above 120 ppm, that's often what's pushing pH up. Lowering alkalinity with acid will also bring pH down — you may be able to solve both at once.
If you find yourself constantly fighting high pH, the root cause is usually high alkalinity. Total alkalinity acts as a buffer for pH — when it's too high (above 120 ppm), it fights against any pH adjustments you make and pushes pH back up. Bring alkalinity into the 80-120 ppm range and pH becomes much easier to hold.
Tell Wade your pH reading and pool size and he'll give you the exact amount to add. No tables, no math, no guessing.
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