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How to raise alkalinity in a pool
Baking soda is the standard fix. It is plain sodium bicarbonate, the same as the pool-store "alkalinity increaser", and it costs less from a grocery or warehouse store.
Steps
- Test alkalinity and work out the rise you need.
- Broadcast the baking soda across the deep end with the pump running.
- Wait 6 hours, then retest. Add no more than about 2 lb per 10,000 gallons in one go.
How much baking soda
| Pool size | +10 ppm | +30 ppm | +50 ppm |
|---|---|---|---|
| 5,000 gal | 11 oz | 2.1 lb | 3.5 lb |
| 10,000 gal | 1.4 lb | 4.2 lb | 7 lb |
| 15,000 gal | 2.1 lb | 6.3 lb | 10.5 lb |
| 20,000 gal | 2.8 lb | 8.4 lb | 14 lb |
| 30,000 gal | 4.2 lb | 12.6 lb | 21 lb |
Check the label if you buy a branded increaser: if it lists sodium bicarbonate only, the dose is the same.
Baking soda or soda ash?
Use baking soda to raise alkalinity, because it moves pH very little. Use soda ash when the problem is low pH. It raises pH strongly and adds alkalinity too. Calculate your exact dose.