Total alkalinity (TA)
Also called: TA, alkalinity.
Total alkalinity (TA) is the buffer in pool water that keeps pH from swinging. Hold total alkalinity at 60–80 ppm, with 50–90 acceptable, which is Trouble Free Pool's recommended level; the 80–120 on pool-store charts and salt-cell manuals is the public-pool operator figure.
Why it matters
TA is pH's shock absorber, but it is also the reservoir of CO₂ that drives the upward creep: the higher your alkalinity, the faster and more stubbornly pH climbs. If pH won't stay put, lower the alkalinity first. Acid lowers pH and TA together, then aeration brings pH back up while TA stays down. Run a salt pool or a heavily aerated one at 60 ppm; about 50 is a floor, not a target. Baking soda raises TA. One catch: CYA registers on an alkalinity test, so water-balance math subtracts about CYA ÷ 3.
In numbers
About 1.5 lb of baking soda per 10,000 gallons raises TA ~10 ppm. Add about three-quarters of the dose, circulate, and retest.