Pool pH Calculator
Enter your current and target pH along with your TA and CYA — we'll estimate the acid (or soda ash/borax) dose.
Dose
Safety first
- Never mix chemicals together.
- Always add the chemical to the water — never water to the chemical.
- Wear gloves and eye protection when handling pool/spa chemicals.
- Keep chemicals out of reach of children and pets.
- Always follow the product label — it overrides any guidance here.
How it's calculated
Lowering pH uses a simplified carbonate-buffer model based on your TA and CYA. Raising pH with soda ash or borax uses community rule-of-thumb doses. Both are estimates — always retest and add gradually.
Ideal pH range
Keep pH between 7.2 and 7.8, ideally 7.4-7.6.
Frequently asked questions
Why doesn't a fixed amount of acid always drop pH the same way?
Your total alkalinity (TA) acts as a buffer — the higher your TA, the more acid it takes to move your pH by the same amount. We use your TA (and CYA) to estimate this.
Should I use muriatic acid or dry acid?
Both work. Muriatic acid is cheaper per use but fumes and should be added carefully, away from your face, ideally with the pump running. Dry acid (sodium bisulfate) is easier to handle but costs more per dose.
I don't want to use acid — how else can I lower pH?
Aeration (fountains, waterfalls, running the pump with a return jet above water) raises pH over time by releasing CO2 — this is actually the opposite effect. To lower pH without chemicals, you would need to reduce aeration, which is slow and not very controllable. Acid is the standard method.
How much should I add at once?
Never add more than the equivalent of about 1 quart of muriatic acid per 10,000 gallons in a single dose. For larger adjustments, split it into steps: add some, wait 30 minutes with the pump running, retest, and repeat.