Low pH is rarer than high pH in Ellis County, but when it happens it usually happens fast — heavy rain, a shock dose with the wrong product, or the slow drift you get on a trichlor-tablet pool. And the standard fix, "throw in some pH up," is right in concept and wrong in execution.
Here's the trap: most "pH up" products are sodium carbonate, also known as soda ash. Soda ash raises pH and raises total alkalinity at the same time. If your TA is already high, raising it further is going to give you a different problem — pH that won't stay where you put it, scaling on plaster and inside the salt cell, and chlorine that doesn't work as well as it should.
So here's how to actually do it.
Test before you decide
If your pH is low, the first question is: is your alkalinity also low?
Low pH + low TA: great. Use soda ash. It'll fix both.
Low pH + normal TA: use soda ash, but expect a small bump in TA. Usually fine.
Low pH + high TA: this is the hard case. Adding soda ash will make TA worse. Better answer is aeration (turn on your fountain or waterfall, point a return jet up so it breaks the surface) — that drives pH up without raising TA.
This sounds fiddly. It's not. It's just two readings instead of one before you grab a bag.
Target ranges
pH: 7.4–7.6
Total alkalinity: 80–120 ppm (some salt-system manufacturers prefer 60–80)
If both are below that, you have room to dose freely. If only pH is low, take it slow.
How much soda ash to add
To raise pH by 0.2 in a 20,000-gallon pool, you need roughly 12 oz of soda ash. That's a rough planning number. Real dose depends on your starting pH, target pH, and current TA. The Soda Ash Calculator handles that math.
Doing it right
Test pH and TA before you start.
Calculate the dose. Don't guess.
Dissolve soda ash in a bucket of pool water before adding. Adding it dry can cloud the pool for hours.
Pour around the deep end with the pump running.
Wait 6 hours and retest. Soda ash needs full circulation to read accurately.
Don't add anything else for the rest of the day. Especially not muriatic acid — you'll just undo what you did.
When you really shouldn't use soda ash
If your TA is already over 120 ppm, don't add soda ash. Aerate the pool instead. A few hours of running your waterfall, fountain, or upturned return jet will pull pH up without touching alkalinity.
Borax — the alternative
Some homeowners use borax (sodium tetraborate) to raise pH. Borax raises pH faster than soda ash and barely touches TA. It also adds borate to the water, which is actually a benefit at moderate levels — it stabilizes pH and provides mild algae prevention. It costs more upfront, but it's a legitimate option if you're fighting persistent pH drop without low TA.
When to call us
If you're treating low pH more than once a month, something else is going on. The most likely cause is an over-stabilized pool with too much trichlor tablet residue. The fix isn't more soda ash — it's switching sanitizer source and getting CYA back to a reasonable range. That's a chemistry-overhaul visit, not a routine dose.
Run the Soda Ash Calculator or call Thomas directly at (214) 399-7347.
