Pool Total Alkalinity Calculator (TA Adjustment)
Sodium bicarbonate dose to raise TA, or muriatic acid dose to lower TA, into the 80-120 ppm safe range for stable pool pH.
Total alkalinity is the pH buffer. TA does not change pool feel directly — it controls how stable your pH is. Low TA means pH bounces around with every chlorine addition. High TA locks pH at the high end and resists adjustment.
Target range: 80-120 ppm. Some pool stores push 100-150. The 80-120 range is closer to optimal because it gives enough buffering without making pH adjustments hopeless. If you have a saltwater pool with a salt cell that strips out CO₂, lean toward the lower end (60-80) to compensate.
To raise TA:
- Sodium bicarbonate (baking soda) — the standard. Cheap, safe, and gentle.
- Reference dose: 1.5 lb per 10,000 gallons raises TA by 10 ppm. Also raises pH very slightly.
To lower TA:
- Muriatic acid is the only practical option for backyard pools. The trick is the technique. Pool acid lowers TA AND pH together at first, but with proper aeration the pH bounces back up while TA stays low.
The “acid wash and aerate” method:
- Add acid in a single concentrated spot (in front of a return on circulation off, or just in the deep end).
- Let it sit briefly to do localized damage to the alkalinity.
- Turn pump on and aerate hard (waterfall, fountain, jets pointed up).
- Aeration drives off CO₂ which raises pH back up — but TA stays where the acid put it.
Reference dose: 26 fl oz of 31.45% muriatic per 10,000 gal lowers TA by 10 ppm (with proper aeration to recover pH).
Worked example. 20,000 gal pool, current TA 60, target 90.
- Raise needed = 30 ppm
- Sodium bicarb dose = 1.5 lb × (30/10) × (20,000/10,000) = 9 lb
That is a big dose. Spread it over 2-3 days to avoid pH spike.
Common mistake. People chase TA and pH at the same time and end up cycling. Fix TA first (get into the 80-120 band), then adjust pH separately. Treat them in order, not together.
Saltwater note. Salt cells generate hydroxide ion which slowly raises pH and can pull CO₂ out. Saltwater pools tend to drift toward high pH, so most owners run lower TA (60-80) to make pH easier to manage.