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How much baking soda
to raise pool alkalinity

Total alkalinity below about 80 ppm makes pH jumpy — every splash of rain or chlorine swings it. The fix is plain baking soda, and the right amount is a function of your pool volume and how far you're lifting it. Here is the chart.

Dosage chart · baking soda for TA

Raise TA by	5,000 gal	10,000 gal	15,000 gal	20,000 gal	25,000 gal
+10 ppm	11.2 oz	1 lb 6.4 oz	2 lb 1.6 oz	2 lb 12.8 oz	3 lb 8 oz
+20 ppm	1 lb 6.4 oz ×2	2 lb 12.8 oz ×2	4 lb 3.3 oz ×2	5 lb 9.7 oz ×2	7 lb 0.1 oz ×2
+30 ppm	2 lb 1.6 oz ×3	4 lb 3.3 oz ×3	6 lb 4.9 oz ×3	8 lb 6.5 oz ×3	10 lb 8.1 oz ×3

Swipe the table sideways for larger pools →

Amounts are baking soda (sodium bicarbonate) by weight. ×2 / ×3 = too much for a single addition — split the total into that many doses, brushing away any piles between additions. Retest after about 6 hours; alkalinity readings drift while the water mixes.

Example: to lift a 10,000-gallon pool from 60 to 70 ppm, add 1 lb 6.4 oz of plain baking soda. The 1-lb boxes from the grocery store are the same sodium bicarbonate as "alkalinity increaser" — the pool-store label mostly buys a bigger bucket.

Baking soda vs soda ash — which one do you need?

They look alike and both nudge both numbers, but they are different tools: baking soda raises alkalinity with only a small pH effect; soda ash raises pH — and drags TA up with it as a side effect.

The engine puts a number on that side effect: raising pH 7.0 → 7.4 in a 10,000-gallon pool takes about 1 lb of soda ash and adds roughly 11.3 ppm of TA at the same time. So the order matters: if both pH and TA are low, fix pH with soda ash first, retest, and only then top up TA with baking soda — otherwise you overshoot alkalinity and end up lowering it again with acid.

Lowering TA is the opposite, asymmetric job: acid plus aeration, done in rounds. There is no "alkalinity decreaser" powder that skips the rounds.

Before you add anything

Test first, dose second. The chart assumes your test number is real — retest a surprising reading before correcting it.
Broadcast it over the deep end with the pump running, rather than dumping it in one spot.
Don't chase pH the same day. Baking soda barely moves pH, but the water needs hours to mix; read TA again before touching anything else.
Hot tubs are not small pools — the volumes here start at 5,000 gallons. For a 300–500 gallon spa the amounts are tablespoon-scale and overshoot is easy; compute them, don't eyeball them.

Your pool, your products

PoolDose (iOS) runs this same engine on your actual pool volume: enter the test reading and the target, and it returns the dose in your units, splits additions that are too large, and tells you when to retest. One-time purchase, no subscription. There's also a free browser calculator for chlorine.

Where these numbers come from

The chart is generated by the same dosing engine that runs inside PoolDose (make-alkalinity.mjs executes it), so this page and the app cannot drift apart. Coefficients are ingredient-based (sodium bicarbonate at 59.56 ppm-yield) and checked against published dosing tables. Estimates for typical residential water — your test kit has the final word.