How to raise pH in a pool
Soda ash is the fast fix, borax is gentler on alkalinity, and aeration is free. Enter your numbers to see each dose and what it does to alkalinity.
Pick one
How to add it
- Pump running. Pre-dissolve in a bucket of pool water (borax dissolves slowly).
- Pour in front of a return jet, spread along the deep end.
- Retest after 1–2 hours of circulation.
Chemical safety: read the product label first and follow it where it differs from this page. Add acid to water, never water to acid. Never mix chlorine products with acid or with each other, not even in a bucket. Add one chemical at a time with the pump running, wait at least 30 minutes (acid and chlorine: until the next test), and retest before topping up.
Soda ash, borax, baking soda or air?
| Method | Raises pH | Raises TA | Use when |
|---|---|---|---|
| Soda ash (sodium carbonate) | Strongly | Yes | pH low, TA low or normal |
| Borax (20 Mule Team, decahydrate) | Moderately | Less | pH low, TA already fine |
| Baking soda (sodium bicarbonate) | Slightly | Strongly | TA low (pH follows) |
| Aeration | Slowly | No | pH low, TA high |
Why doses depend on alkalinity
Alkalinity is the water’s buffer. The more carbonate there is, the more base it takes to move pH by the same amount, which is also why pH barely moves in a high-TA pool and swings wildly in a low-TA one. See the buffer explainer on the alkalinity calculator, and the chlorine side of the story on lowering pH.
Questions pool owners ask
What is the fastest way to raise pH in a pool?
Soda ash (sodium carbonate, sold as pH Up or pH Increaser). It raises pH quickly and also raises alkalinity. Add it to the water in front of a return jet with the pump running, no more than about 1 lb per 10,000 gallons per dose to avoid clouding.
Does baking soda raise pH?
Only a little. Baking soda mainly raises total alkalinity; it nudges pH up towards about 8.3 at most, so it’s a gentle way to raise both when both are low. If only pH is low and alkalinity is fine, use soda ash, borax or aeration.
Can I raise pH without raising alkalinity?
Yes, by aeration. Run waterfalls, point returns upward, or run a spa spillover. Escaping carbon dioxide raises pH while leaving alkalinity unchanged. It is slow (hours to days) but free. Borax also raises pH with a smaller alkalinity rise than soda ash.
Why is my pool pH low?
Common causes are trichlor tablets (acidic), heavy rain, too much acid added last time, and low total alkalinity that lets pH swing. If alkalinity is under 60 ppm, fix that first with baking soda.
Is low pH dangerous?
CDC recommends pH 7.0–7.8. Below 7.0 the water becomes corrosive: it can etch plaster, damage heat exchangers and pump seals, and irritate eyes and skin. Chlorine also gets used up faster.