Alkalinity calculator
Add about 6.8 lbs of baking soda (sodium bicarbonate) to raise TA by 30 ppm. Add in thirds, circulating and retesting between.
Treat this as a starting dose: add less than the full amount when unsure, circulate for a few hours, retest, repeat. Always follow your product's label.
Low total alkalinity makes pH bounce around unpredictably — it's the buffer that keeps pH stable, so when it's low, nothing holds. Raising it is a simple, low-drama job with baking soda. Here's how. Follow the product label and confirm your pool volume first.
Why low alkalinity is a problem
Total alkalinity (TA) buffers the water against pH swings. When TA drops below about 80 ppm, pH becomes unstable — it can crash or spike from small additions or even rain — and low TA can also make water corrosive to surfaces and equipment. If your pH won't hold still and reads erratically, low alkalinity is a prime suspect. The target for most pools is roughly 80–120 ppm, and getting TA into that band steadies everything downstream.
The tool: sodium bicarbonate
You raise alkalinity with sodium bicarbonate — the same thing as baking soda, sold in bulk as an alkalinity increaser. It's one of the gentler, more forgiving pool chemicals: it raises TA effectively and nudges pH up only modestly, so it's hard to cause a problem with. Test TA and pH first, confirm your pool volume, and read the label for how much product raises TA by a given amount in your gallons. That lets you dose toward the target instead of guessing.
Add, circulate, retest
Dose with the pump running. Broadcast the measured amount of sodium bicarbonate across the pool surface (or dissolve and pour it in) while the water circulates, then let it mix for several hours before retesting. If you have a lot of ground to make up, add in stages rather than one huge dose — retest between rounds and add more as needed. Because baking soda is gentle, this rarely overshoots, but staged dosing keeps you precise.
Then check pH
Rebalance pH after. Raising TA will lift pH a little, so once alkalinity sits in the 80–120 ppm range, retest pH and adjust it into the 7.2–7.6 range if needed. Do alkalinity first, pH second — that order keeps you from chasing the two around each other. Once both hold steady across a couple of tests, you're done, and your chemistry will be far more stable going forward. Our alkalinity calculator sizes the dose from your volume and current reading.
If it keeps dropping
Address recurring lows. If TA constantly falls, look at what's pulling it down — heavy rain diluting the water, lots of fresh fill water with low alkalinity, or repeated acid additions to lower pH can all erode TA. Fixing the cause (or simply staying ahead of it with routine bicarb additions) beats re-dosing blindly. Steady alkalinity is the foundation of a pool that doesn't fight you every week.
Frequently asked questions
How do I raise alkalinity in a pool?
Test total alkalinity, confirm pool volume, then add an alkalinity increaser such as sodium bicarbonate according to the product label. Circulate the water, retest, and adjust again only if needed.
What raises pool alkalinity without raising pH too much?
Sodium bicarbonate is the common product used to raise total alkalinity. It can move pH somewhat, but it usually affects alkalinity more than pH when used carefully.
Can I use baking soda to raise pool alkalinity?
Many alkalinity increaser products are sodium bicarbonate, which is also baking soda. Use a pool-labeled product or carefully follow the product label so you know dose strength and purity.
What happens if pool alkalinity is too low?
Low alkalinity makes pH easier to swing up and down. That can lead to uncomfortable water, sanitizer problems, corrosion risk, and a pool that behaves like it had too much coffee.
Should I fix alkalinity or pH first?
If alkalinity is clearly low, fix alkalinity first, then retest pH. Alkalinity acts like the buffer for pH, so chasing pH before fixing the buffer can waste chemicals.
How soon can I retest after adding alkalinity increaser?
Follow the product label. A practical routine is to circulate thoroughly, brush any settled product, wait for the water to mix, then retest before adding more.
