Water Chemistry

Baking Soda vs Soda Ash vs Borax for Pools

Three white powders, three different jobs. Pick by which reading is low.

Updated November 2026

Short answer

Use baking soda when total alkalinity is low. Use soda ash when pH is low and alkalinity could also use a lift. Use borax when pH is low but alkalinity is already where you want it.

All three raise both numbers to some degree. The difference is which number moves most.

Baking soda calculator

For pH, use the soda ash calculator.

What is the difference between the three?

Baking soda, soda ash and borax compared for pool use
	Baking soda	Soda ash	Borax
Chemical name	Sodium bicarbonate	Sodium carbonate	Sodium tetraborate
Sold as	Alkalinity increaser	pH increaser, pH up	Laundry booster
Effect on pH	Small rise	Strong rise	Moderate rise
Effect on alkalinity	Strong rise	Moderate rise	Smaller rise
Typical dose per 10,000 gallons	1.4 lbs raises alkalinity 10 ppm	6 oz raises pH about 0.2	About 16 to 20 oz raises pH about 0.2
Risk of clouding the water	Low	Higher, if added fast	Low

Doses are starting points. How far pH moves depends on your alkalinity, so add part of the dose, circulate and retest.

Which one should I use?

Alkalinity under 80 ppm, pH about right: baking soda. It lifts alkalinity with only a small nudge to pH.
pH under 7.2 and alkalinity also low: soda ash. One product fixes both.
pH under 7.2 but alkalinity already 100 ppm or more: borax. It raises pH while adding less alkalinity than soda ash.
Both very low: raise alkalinity first with baking soda, wait several hours, retest, then correct pH.

If pH is only slightly low and alkalinity is fine, try aeration first. Pointing the return jets up so the surface ripples raises pH with no chemicals at all.

How do I add them safely?

Test pH and total alkalinity, and know your pool volume. The volume calculator helps if you are unsure.
Run the pump and spread the powder over the deep end. Dissolve soda ash in a bucket of pool water first to avoid a cloud.
Add no more than about 2.8 lbs of baking soda (a 20 ppm rise) or 1 lb of soda ash per 10,000 gallons at one time.
Wait before adding more: 2 to 3 hours of circulation after soda ash or borax, at least 6 hours after baking soda. Then retest and repeat only if needed.

Never add any of these at the same time as calcium chloride or right after it. Space them at least a few hours apart, or the water can turn milky.

Frequently Asked Questions

Is grocery store baking soda the same as pool alkalinity increaser?

Yes. Both are sodium bicarbonate. Plain baking soda in large bags is the same chemical and usually costs less per pound.

Is washing soda the same as soda ash?

Yes. Washing soda is sodium carbonate, the same chemical sold as pool pH increaser. Check that the box lists sodium carbonate with no added scent or detergent.

Can I use baking soda to raise pH?

Only a little. Baking soda cannot push pH much above 8.3 and it takes a lot of it to move pH at all, which overshoots alkalinity. For low pH, soda ash or borax is the right choice.

Does borax add anything else to the water?

It adds borate. In the small amounts used to adjust pH this is not a concern, but it does build up over time because borate only leaves the pool when water is drained or splashed out.

Sources

Get the exact amount

Enter your pool size and readings and get pounds or ounces, with a warning when a dose should be split.

Baking Soda Calculator Soda Ash Calculator