Vinegar works for small pH adjustments.

Yes, you can use white vinegar or citric acid to lower pool pH without buying a dedicated decreaser.

The catch is concentration. Muriatic acid is about 30% hydrochloric acid — strong stuff. Household vinegar is only 5% acetic acid. You’ll need a lot more vinegar to move the needle. For a typical 10,000-gallon pool, you might need a gallon or more of vinegar to drop pH by 0.2. That gets expensive and can mess with your alkalinity.

Citric acid works similarly — it’s the same stuff you use for canning or cleaning. Available at grocery stores. But again, you need volume.

If your pH is only slightly high (7.8–8.0), vinegar is fine. For bigger corrections, or if you want results fast without cloudiness, just buy the pool store stuff. Natural doesn’t always mean better.

Don’t expect vinegar to fix a pH of 8.4 quickly. Start with a gallon, wait a few hours, retest. And never mix vinegar with chlorine — you’ll make chlorine gas. That’s not a pool problem, that’s a breathing problem.