Pool Alkalinity Calculator
Total alkalinity (TA) keeps your pH stable. Target range: 80–120 ppm. The standard fixer is ordinary baking soda (sodium bicarbonate) — the same box from the grocery store.
How the math works
- Baking soda: 1.5 lbs per 10,000 gallons raises TA by about 10 ppm → lbs = Δppm × gallons ÷ 10,000 × 0.15
- Soda ash: 1 lb per 10,000 gallons raises TA by about 11 ppm, but it also pushes pH up — use it when both TA and pH are low
Before you add
- Test TA with a reliable test kit (drop-based tests are more accurate than strips).
- Add baking soda in two or three portions, brushing between doses, rather than all at once.
- Retest after 4–6 hours of circulation. If pH drifts up too much after soda ash, use muriatic acid to bring it back down.
- Never mix chemicals together — always add one product at a time, with the pump running.
Frequently asked questions
Can I use Arm & Hammer baking soda from the grocery store?
Yes. Grocery-store baking soda and "alkalinity increaser" pool chemicals are the same compound (sodium bicarbonate). The pool-store version is often just repackaged — and more expensive.
My TA is high. How do I lower it?
Lower TA with muriatic acid, then aerate (returns, spa jets, air compressor) to raise pH back up without raising TA. Repeat as needed — this is called the acid/aeration method.
Why does my pH keep drifting up?
Rising pH with falling TA usually means aeration (waterfalls, spillovers, features) is driving CO₂ out of the water. Lower TA into the 60–80 ppm range to make pH easier to hold.