How to Raise Total Alkalinity in a Pool

If your pH keeps drifting no matter how carefully you dose it, or a test strip reads total alkalinity below 60 ppm, the fix usually isn't more pH adjuster. It's baking soda. Total alkalinity (TA) is what keeps pH stable between tests, and when it's too low, pH becomes a moving target that never quite settles, even if you're testing and correcting it faithfully every few days. Here's how to raise total alkalinity, how much baking soda to use, and why it's worth handling before you touch pH at all.

Why total alkalinity comes before pH

Total alkalinity is often described as a buffer, and that's the right word for it. It's a measure of how much dissolved bicarbonate is in the water, and that bicarbonate resists sudden pH changes the way a shock absorber resists a bump. When TA is in range, pH moves slowly and predictably in response to sun, rain, bathers, and chemicals. When TA is low, pH has nothing holding it steady, so it can swing several tenths of a point overnight for no obvious reason, even when nothing about the pool has visibly changed. Pool professionals call this pH bounce, and it's one of the most common reasons someone feels like they're "always chasing pH" no matter how often they test. Raising TA first generally settles that bounce down, which is what makes every pH adjustment after that actually stick instead of drifting back within a day or two.

What causes total alkalinity to drop in the first place

Low TA rarely comes out of nowhere. A few common causes: heavy rain dilutes the water and pulls TA down along with everything else. Fresh fill water from a hose, especially after a top-off or a partial drain, can start out lower in alkalinity than your pool needs. And ironically, correcting pH with muriatic acid or dry acid lowers TA as a side effect, so a pool that's had its pH aggressively corrected over several weeks can end up with fine pH and quietly depleted alkalinity. Saltwater pools can also see TA drift down gradually as the chlorinator runs, which is one more reason to check TA on its own schedule rather than only when pH looks off.

How much baking soda to add

Sodium bicarbonate, plain baking soda, is the standard product for raising total alkalinity. A commonly used rule of thumb is that about 1.5 pounds of baking soda per 10,000 gallons of pool water raises TA by roughly 10 ppm. So if you're testing at 50 ppm and want to land in the ideal 80-120 ppm range, you're looking at raising it by about 40 ppm, which works out to roughly 6 pounds of baking soda for a 10,000-gallon pool, scaled up or down for your actual pool size. Skimmer's total alkalinity calculator can do this math for you once you enter your pool's volume and current reading, so you're not doing the arithmetic poolside with a bag of baking soda in one hand and a phone in the other.

These figures are estimates, not guarantees. Actual results vary with your pool's exact volume, how well it circulates, and what else is already dissolved in the water. Always add chemicals gradually and retest before dosing again rather than assuming the math landed exactly where you calculated, and treat the number as a starting point for your first dose rather than the whole answer.

• Test current TA with a liquid kit or test strips so you know your real starting point, not a guess.
• Calculate the dose using the ~1.5 lb per 10,000 gallons per 10 ppm rule, or let a calculator handle it.
• Broadcast the baking soda slowly across the widest part of the pool surface with the pump running, rather than dumping it in one spot.
• Let the pump circulate for at least a few hours, ideally overnight, before you brush or vacuum anything that settles.
• Retest the next day. If you're still under range, repeat with a fresh dose based on the new reading rather than guessing at a second round.

What happens to pH after you raise TA

Baking soda is mildly alkaline on its own, so raising TA will typically nudge pH up a little too, just not nearly as much as soda ash would. That's usually a welcome side effect if your pH was also low, but if your pH was already fine, expect it to creep up slightly over the following day. Don't rush to correct it right away. Give the water 24 hours to settle after a TA dose, retest both TA and pH together, and only then decide whether pH needs its own adjustment. Adjusting pH before TA has finished settling is a common way people end up chasing both numbers back and forth for a week, correcting pH, watching TA shift it again, and never quite landing on stable water.

Once both numbers hold steady across a couple of weekly tests, you're done, at least until the next heavy rain or refill resets the clock. Logging the dose and the date makes the next round faster, since you'll have a real starting point instead of guessing whether last month's baking soda actually took effect.