How to Raise Pool Alkalinity with Baking Soda
By The Aqualitx team at STEMania · Updated
Total alkalinity is the pool's pH buffer. When it's too low, pH bounces around and is hard to hold anywhere. The fix is almost always plain sodium bicarbonate — the same baking soda in your kitchen, sold in bigger bags as "alkalinity increaser."
What total alkalinity should be
Keep total alkalinity (TA) between 80 and 120 ppm. Below 80, pH swings with every rainstorm and acid dose, and low-pH water starts etching plaster and corroding metal. Above 120, pH tends to climb steadily and needs constant acid.
Pools with salt cells or lots of aeration often do better near the low end (80–90 ppm), because high alkalinity drives pH up faster.
How much baking soda to add
The rule of thumb: about 1.5 lbs of sodium bicarbonate per 10,000 gallons raises alkalinity by about 10 ppm. So to take a 15,000-gallon pool from 60 to 100 ppm (a 40 ppm rise):
- 40 ppm ÷ 10 = 4 steps of 10 ppm
- 4 × 1.5 lbs = 6 lbs per 10,000 gallons
- 6 lbs × 1.5 (for 15,000 gallons) = 9 lbs total
The alkalinity calculator does this for any volume.
How to add it
- Run the pump.
- Broadcast the baking soda across the surface of the deep end, or pre-dissolve it in a bucket of pool water and pour it around the pool.
- Brush any powder that settles on the floor.
- Wait about 6 hours with the pump running, then re-test alkalinity and pH.
Expect pH to rise a little
Baking soda nudges pH up slightly as it raises alkalinity. That's normal. Re-test before adding acid: if you dose acid against the pH you read before the baking soda went in, you're working from a number that has already changed.
Don't add it with calcium
Never add calcium chloride (calcium hardness increaser) on the same day as baking soda or soda ash. Together they can cloud the water. Dose them a day apart.
Baking soda vs soda ash
They sound similar but do different jobs. Baking soda (sodium bicarbonate) raises alkalinity a lot and pH a little. Soda ash (sodium carbonate) raises pH a lot and alkalinity some. If alkalinity is low, use baking soda. If alkalinity is fine and only pH is low, soda ash is the faster tool.
Why alkalinity drops
Acid is the main culprit: every dose to lower pH also lowers alkalinity. Rain dilutes it, and trichlor tabs slowly consume it. If you're adding acid regularly, plan on topping up alkalinity every so often — see how to lower pool pH for the other half of that cycle.