💧 pH & Alkalinity Balance Order
When both readings are off, the order matters more than the amounts. Enter your volume and your two current readings to get the sequence, and what each step does to the other number.
🧪 Your readings
Why this needs its own page
Our pH & alkalinity calculator tells you how much of one chemical to add to move one reading, and says plainly in its own notes that these chemicals also nudge the other reading. That is the honest limit of a one-at-a-time tool, and it is exactly where most people get stuck: they fix pH, watch alkalinity drift, fix alkalinity, watch pH drift, and conclude the test kit is wrong.
It is not the kit. Acid lowers both. Soda ash raises both. Baking soda raises both, just in very different proportions. The only way through is to take them in the right order — alkalinity first, because it buffers pH — and to know what each step leaves the other reading at before you add the next thing.
And there is one combination with no chemical answer at all: low pH when alkalinity is already near the top of its band. Soda ash would lift the pH and push that alkalinity straight over. Aeration is the only lever that raises pH and leaves alkalinity exactly where it is, because it works by driving off carbon dioxide rather than adding anything. This page tells you when you are in that corner.
❓ Frequently Asked Questions
Why can't I just fix pH and alkalinity separately?
Because no pool chemical moves one reading on its own. Muriatic acid lowers pH and takes alkalinity down with it. Soda ash raises pH and nudges alkalinity up. Baking soda raises alkalinity and lifts pH a little. Correct one in isolation and you move the other out of range, which is why so many people feel they are chasing their own tail with a test kit.
Why does alkalinity get corrected before pH?
Total alkalinity is pH's buffer — it is what resists a change in pH. Set pH against the wrong alkalinity and it drifts back within days, because nothing is holding it. Set alkalinity first and pH becomes stable enough to be worth correcting. That ordering is the single most useful thing on this page.
My pH is low but alkalinity is already high. What do I add?
Nothing — this is the case with no chemical answer, and it is the one aeration exists for. Soda ash would raise pH, but it would push an alkalinity that is already near the top of the band straight over it. Aeration raises pH by driving off carbon dioxide and does not change alkalinity at all: run water features, angle the return jets upward, or drop in an air line. It is slow and it is free. (If BOTH readings are low there is no such problem — baking soda sets alkalinity, and soda ash then has room to lift pH.)
How accurate are the amounts?
They use the same published dosing rates as our pH and alkalinity calculator, scaled by your pool volume, so on a single-reading correction the two pages agree exactly. Pool chemistry is not linear across large swings, though, and your fill water, stabiliser and calcium hardness all have a say. Dose gradually, circulate, and re-test rather than adding a big correction at once.
What are the ideal ranges?
pH 7.4 to 7.6 and total alkalinity 80 to 120 ppm are the commonly published targets, and this tool aims for the middle of both. Slightly outside is not an emergency; a long way outside damages surfaces and equipment and stops chlorine working properly.