Total Alkalinity Adjustment Formula
The Formula
Sodium bicarbonate (oz) = Desired TA Increase (ppm) × Volume (gal) × 0.000224
| Symbol | Description | Unit |
|---|---|---|
TA Increase | Target TA minus current TA in ppm | ppm |
Volume | Pool volume in gallons | gallons |
0.000224 | Ounces of sodium bicarbonate needed per ppm per gallon (1.4 lbs per 10,000 gal per 10 ppm) | oz/ppm/gal |
Worked Example
Example
Pool: 18,000 gallons. Current TA: 60 ppm. Target TA: 100 ppm.
- TA increase needed = 100 − 60 = 40 ppm
- Dose = 40 × 18,000 × 0.000224 = 161.3 oz = 10.1 lbs
Add approximately 10 lbs of sodium bicarbonate. Split into two additions if needed, waiting 4–6 hours between tests.
How This Formula Works
Total alkalinity (TA) is the pool's buffering capacity — it resists pH changes. Low TA causes pH to swing wildly with minor additions. High TA makes it difficult to lower pH.
- To raise alkalinity: sodium bicarbonate (baking soda). 1.4 lbs per 10,000 gallons raises TA by approximately 10 ppm, matching published pool-operator dosage tables (Indiana Department of Health's "Water Chemistry Adjustment Guide," adapted from the National Swimming Pool Foundation Pool & Spa Operator Handbook).
- To lower alkalinity: muriatic acid. Adding acid lowers both pH and alkalinity. To specifically lower TA without driving pH too far down, add acid with the pump off, then aerate to bring pH back up.
- The 0.000224 constant is equivalent to 1.4 lbs (22.4 oz) raising TA by 10 ppm in 10,000 gallons.
Limitations & Notes
Sodium bicarbonate also causes a slight pH increase — usually 0.1 to 0.2 pH units for typical doses. Recheck and adjust pH after alkalinity correction if needed. TA should be stabilised before making pH adjustments.
Last reviewed: 2026-08-28