Can I use vinegar to lower my pool pH instead of buying a dedicated decreaser?

Yes, white vinegar or citric acid works for small pH adjustments (7.8–8.0), but you’ll need a lot more than muriatic acid — a gallon or more for a 10,000-gallon pool to drop pH by 0.2. It’s fine for minor tweaks, but for bigger corrections or fast results, just buy the pool store stuff. Never mix vinegar with chlorine — that creates chlorine gas.