Water, clarity and algae
Adjusting pool alkalinity
Total alkalinity holds the pH steady. Adjusting it is done in small steps, because overshooting sends the pH swinging.
Total alkalinity is the buffer that holds the pH steady, and when it is out of range the pH swings with every dose and every rain. Raising it is done with an alkalinity increaser; lowering it is done with acid. Both are done in steps, with the water retested between them.
Water guides explain what a reading or a symptom means and the order in which to correct it.
The order matters: alkalinity is corrected before chasing the pH, because the pH will not stay put while the buffer is wrong. Small, measured adjustments and a retest each time keep the pool from overshooting and having to be corrected back the other way.
The short version
What it does
Alkalinity buffers the pH so it does not swing with every change.
Raise or lower
An increaser raises it; acid lowers it, both in small measured steps.
Fix it before pH
The pH will not stay put while the buffer is out of range.
How the adjustment is done
Raising alkalinity
An alkalinity increaser is added in steps, with the water retested between them.
Lowering alkalinity
Acid is added in steps, following the product and the water volume.
Retesting
Each step is followed by a retest, so the pool is not overshot.
Before adjusting
Test first
The current alkalinity and pH, so the right amount is added.
Know the volume
The dose follows the water volume, not a guess.
Adjust in steps
Whether the change is made in small amounts with retests.
In practice
Correct the alkalinity before chasing the pH, because the pH will not stay put while the buffer is wrong. Raise it with an increaser, lower it with acid, and do both in small measured steps with a retest between each one so the pool is not overshot.
Mistakes to avoid
Fixing pH before alkalinity
The pH will not hold while the buffer is out of range. Correct the alkalinity first.
Overshooting in one step
A large adjustment overshoots and sends the pool the other way. Small steps with retests stay on target.
Common questions
Why does my pH keep swinging?
Usually the total alkalinity is out of range, so the buffer is not holding the pH. Correct the alkalinity first.
How do I raise alkalinity?
With an alkalinity increaser, added in measured steps to the water volume, with the water retested between steps.
Should I fix alkalinity or pH first?
Alkalinity first, because the pH will not stay put while the buffer is wrong. The pH is corrected after the alkalinity is in range.
Related pool care guides
- When pool pH is too highAnother water problem with a related cause.
- When pool pH is too lowAnother water problem with a related cause.
- Storing pool chemicals safely at homeA routine task that prevents the same trouble.
- Dealing with a contamination incident in a private poolPool care for a related situation.
This guide sits under pool water treatment. Browse all pool care guides. We look after pools at homes and commercial properties across Dubai.
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Next step
pH swinging after every dose?
Tell us your recent alkalinity and pH readings. We will set out the right order and amounts.