Baking soda calculator: raise pool alkalinity
Total alkalinity is the water’s buffer against pH swings. Baking soda raises it with only a small nudge to pH. Enter your test result and target.
Enter your measurements
More options: pH · CYA · Temp
- pH afterwards (estimate)
- 7.5
- Baking soda per 10 ppm in this pool
- 1.4 lb (22.4 oz)
- At the label’s 1.5 lb per 10 ppm per 10,000 gal
- 4.5 lb (72 oz)
In short: each bit of baking soda adds a fixed amount of alkalinity, so the dose is the rise you want times your pool’s size.
Rise: 90 − 60 = 30 ppm (as calcium carbonate)
30 ppm ÷ 50,044 mg per equivalent × 37,854 L = 22.69 mol of bicarbonate
× 84 g per mole = 4.2 lb (pH 7.4 → about 7.5)
- Grocery baking soda and pool “alkalinity increaser” are the same chemical (sodium bicarbonate). Compare price per pound.
Quick answers for common sizes
| Example | Answer |
|---|---|
| How much baking soda to raise alkalinity in a 10,000 gallon pool | 4.2 lb |
| How much baking soda to raise alkalinity in a hot tub | 3.59 oz |
Baking soda for this pool, by target alkalinity
| Target TA | Baking soda to add | pH afterwards (estimate) |
|---|---|---|
| 70 ppm | 1.4 lb | 7.4 |
| 80 ppm | 2.8 lb | 7.5 |
| 90 ppm | 4.2 lb | 7.5 |
| 100 ppm | 5.6 lb | 7.6 |
| 110 ppm | 7 lb | 7.6 |
| 120 ppm | 8.41 lb | 7.6 |
Total alkalinity (TA) is mostly bicarbonate. It soaks up acid and base so pH doesn’t lurch every time it rains or you add chlorine. When TA is low, pH bounces around and drifts down; baking soda — sodium bicarbonate — adds bicarbonate directly.
How much baking soda: the formula
Alkalinity is reported as ppm of calcium carbonate, and each mole of baking soda adds one equivalent (50.04 g as calcium carbonate). So 10 ppm in 10,000 gallons (37,854 L) is 7.56 moles, or 636 g — 1.4 lb. A pool alkalinity label rounds that to “1-1/2 lb per 10,000 gallons raises alkalinity about 10 ppm”, which also allows for a slightly impure product.
pounds of baking soda ≈ 1.4 × (ppm rise ÷ 10) × (gallons ÷ 10,000) grams = ppm rise × litres × 84 ÷ 50,044
| Pool | +10 ppm | +20 ppm | +30 ppm | +50 ppm |
|---|---|---|---|---|
| 5,000 gal | 11.2 oz | 1.4 lb (22.4 oz) | 2.1 lb (33.6 oz) | 3.5 lb (56 oz) |
| 10,000 gal | 1.4 lb (22.4 oz) | 2.8 lb (44.8 oz) | 4.2 lb (67.2 oz) | 7 lb (112 oz) |
| 15,000 gal | 2.1 lb (33.6 oz) | 4.2 lb (67.2 oz) | 6.3 lb (101 oz) | 10.51 lb (168 oz) |
| 20,000 gal | 2.8 lb (44.8 oz) | 5.6 lb (89.7 oz) | 8.41 lb (134 oz) | 14.01 lb (224 oz) |
| 25,000 gal | 3.5 lb (56 oz) | 7 lb (112 oz) | 10.51 lb (168 oz) | 17.51 lb (280 oz) |
Worked pages: how much baking soda to raise alkalinity in a 10,000 gallon pool and how much baking soda to raise alkalinity in a hot tub.
What it does to pH
Bicarbonate sits close to pool pH on its own, so baking soda raises pH only a little — usually a tenth or two, more when alkalinity starts very low. That is why it is the tool for low alkalinity, and soda ash (which raises pH much more per pound) is the tool for low pH with normal alkalinity. The calculator estimates the pH afterwards from the same carbonate model used in the muriatic acid calculator.
What alkalinity to aim for
The Model Aquatic Health Code allows 60–180 ppm in public pools. Many home pools run lower in that range (about 70–100 ppm for plaster) if they use liquid chlorine or a salt cell, which push pH up, and a little higher with trichlor tablets, which are acidic. Your stabilizer counts in an alkalinity test, too: the MAHC annex corrects for it by subtracting a third of the CYA. The saturation index calculator shows how TA, pH, calcium and temperature balance together.
Adding baking soda
- Broadcast it over the deep end with the pump running, or pre-dissolve it in a bucket of pool water. It dissolves easily.
- For big rises, add half, circulate for several hours, retest, then add the rest.
- Don’t add acid and baking soda at the same time — they cancel each other out.
What you’ll need
- Alkalinity increaser (sodium bicarbonate)Budget price
Raises total alkalinity with little change in pH. Pool-labelled bicarbonate and grocery baking soda are the same compound — compare price per pound.
See options on Amazon (opens in a new tab) - Digital scale (to 5 kg / 11 lb)Budget price
Weighs granular chemicals to the ounce. Use a dedicated scale — never the one you cook with.
See options on Amazon (opens in a new tab) - FAS-DPD drop test kit (chlorine, pH, TA, CH, CYA)Mid-range price
A drop-count kit reads free chlorine to 0.5 ppm (or 0.2 ppm), plus pH, alkalinity, calcium and stabilizer. Every dose on this site starts from a test, so this is the one thing worth buying first.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How much baking soda raises alkalinity by 10 ppm?
About 1.4 lb of pure sodium bicarbonate per 10,000 gallons (one pool label rounds it to 1.5 lb). In metric, about 168 g per 10,000 litres.
Can I use grocery-store baking soda in my pool?
Yes. It is the same chemical as pool alkalinity increaser — sodium bicarbonate. Buy whichever is cheaper per pound, and avoid anything with added ingredients.
Does baking soda raise pH?
A little. It mainly raises alkalinity, nudging pH up by about a tenth or two. To raise pH by more, use soda ash — see how much soda ash to raise pH in a 10,000 gallon pool.
How long after adding baking soda can I test alkalinity?
Give it a few hours with the pump running so it mixes through the whole pool, then retest before adding more.
Related guides
Sources
- Leslie’s — Alkalinity Up (sodium bicarbonate) label (opens in a new tab) — 100% sodium bicarbonate; 1-1/2 lb per 10,000 gallons raises total alkalinity about 10 ppm.
- CDC — Model Aquatic Health Code, 5th edition (2024), code (opens in a new tab) — Free chlorine minimum 1.0 ppm (2.0 with CYA, 3.0 in spas); pH 7.0–7.8; CYA at or below 90 ppm; CYA:FC above 45:1 is an imminent hazard; TA 60–180 ppm; turnover tables.
- CDC — Model Aquatic Health Code, 5th edition (2024), annex (opens in a new tab) — CYA reduces chlorine’s effectiveness; correcting total alkalinity for CYA by subtracting CYA ÷ 3.
- USGS — Alkalinity calculator: methods (opens in a new tab) — Temperature-dependent equilibrium constants for water and carbonic acid (after Stumm & Morgan), with activity corrections.
- CDC Healthy Swimming — Home pool and hot tub water treatment and testing (opens in a new tab) — pH 7.0–7.8; free chlorine at least 1 ppm in pools (2 ppm with cyanuric acid) and 3 ppm in hot tubs; no CYA in hot tubs; test twice a day.
- CDC — Pool chemical injuries press release (2014) (opens in a new tab) — Never mix pool chemicals, especially chlorine products with acid; add chemical to water, never water to chemical.