Guide
How to raise or lower pool pH
Updated October 21, 2026
Written by Richard Ellis, Certified Pool Operator
Short answer
Keep pool pH between about 7.2 and 7.8. To lower it, add muriatic acid slowly in front of a return with the pump running. To raise it, add soda ash, or aerate the water with the returns pointed up, which raises pH without raising alkalinity. Retest after a few hours before adding more.
pH is the reading that quietly decides whether everything else works. Chlorine loses strength as pH climbs, high pH leaves scale and cloudy water, and low pH eats plaster and stings eyes. Here is how to move it either way and why it seems to move on its own.
What should the pH be in a pool?
About 7.2 to 7.8, with the low end of that range making chlorine work hardest. The CDC recommends a DPD test kit for checking chlorine and pH at home. The full set of targets is in pool chemical levels for Florida.
How do you lower pH in a pool?
With muriatic acid. Dose it for your gallons by the label, then pour it slowly in front of a return with the pump running, never into the skimmer. Wait a few hours, test, and add more only if you need it. Lowering pH also lowers alkalinity a little.
Dry acid (sodium bisulfate) works too, but Hayward's AquaRite manual discourages it for salt pools in places where the water evaporates without much fresh water added, because its byproducts build up and can damage the salt cell.
How do you raise pH in a pool?
Soda ash (sodium carbonate) raises pH quickly, and it is what Hayward's manual says to use when pH is too low. Aeration raises it more gently: point the returns up so they break the surface, or run a waterfall or fountain, and carbon dioxide escapes from the water. Aeration is the way to raise pH without raising alkalinity.
Can I use baking soda to raise pH?
Only a little. Baking soda raises alkalinity a lot and pH only slightly, so it is the right fix for low alkalinity, not for low pH. See how to raise or lower pool alkalinity.
Why does my pool pH keep going up?
A few Florida regulars push it up:
- A salt cell, which raises pH as it makes chlorine.
- New plaster, which keeps pushing pH up for months.
- Waterfalls, spillovers and jets that splash and aerate.
- High alkalinity, which drags pH up behind it.
If you are adding acid every week, check the alkalinity first. If you would rather someone else kept up with the acid, our weekly pool service balances the water every week, chemicals included.
What happens if pool pH is too high?
Chlorine works much more slowly, so the pool can test fine and still cloud up or turn green, and calcium comes out of the water as haze on the water and scale on the tile. See why is my pool cloudy.
What happens if pool pH is too low?
Low pH water is corrosive. It etches plaster, eats metal parts like heater cores and ladder anchors, and stings eyes. Corroded copper is also where blue green stains come from; see how to remove copper stains.
Can you lower pool pH naturally?
Not in any useful way. Rain nudges it down a little, and vinegar is far too weak for a pool and adds organic material for the chlorine to burn through. Muriatic acid, measured properly, is the practical answer.
Quick answers
- Should I adjust pH or alkalinity first?
- Alkalinity first, because it sets how easily the pH moves. Once alkalinity is in range, pH is far easier to set and hold.
- Can you swim after adding muriatic acid?
- Give it time to mix with the pump running, then test. Once the pH is back in range and the label's wait has passed, it is fine.
- Why does my pH test read purple or strange right after a shock?
- Very high chlorine can throw off the pH test. Wait until free chlorine comes back down before trusting the pH reading.
Sources
Keep reading
How to raise or lower pool alkalinity
Keep total alkalinity around 80 to 120 ppm. To raise it, add sodium bicarbonate (baking soda) a little at...
What should pool chemical levels be in Florida?
Keep free chlorine at least 1 ppm, or at least 2 ppm with stabilizer, and pH between 7.2 and 7.8. Aim for...
How to clean a pool salt cell
Check the salt cell about every three months. If the plates have white, crusty scale, turn off the power,...
Why is my pool cloudy?
Cloudy pool water almost always comes down to one of three things: not enough free chlorine, water that i...
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