Guide
What to do when pool chlorine is too high
Updated October 21, 2026
Written by Richard Ellis, Certified Pool Operator
Short answer
Stop adding chlorine and let the sun do the work: uncovered, a Florida pool drops chlorine quickly on its own. To speed it up, remove any tablets, turn down a salt cell's output, and run the pump. A chlorine neutralizer works fast but is easy to overdo. Swim once free chlorine is back to 5 ppm or lower.
Too much chlorine is the problem people would rather have, and it usually fixes itself in a day or two. Still, it stings eyes, fades swimsuits and throws off your other tests while it lasts. Here is how to bring it down and when the water is fine again.
What is too high for pool chlorine?
For swimming, anything above about 5 ppm free chlorine is higher than you want, which is the same number we use for swimming after a shock in how long after shocking a pool you can swim. For everyday care, the CDC minimum is 1 ppm, or 2 ppm with stabilizer, so a normal target sits a little above that.
How do you lower chlorine in a pool fast?
Take away the source and add sunlight:
- Stop adding chlorine. Pull tablets from the feeder or floater.
- Turn down the salt cell. Lower its output setting; Hayward's AquaRite manual says to lower the output to decrease chlorine.
- Take the cover off and let the sun at it, and run the pump.
- Use a chlorine neutralizer (sodium thiosulfate) only if you need it today, and dose it in small steps, because it is easy to take the chlorine to zero.
How long does it take for chlorine to go down?
Often a day or two in summer sun, longer in winter, under a cover or with a lot of stabilizer, which protects chlorine from the sun. Retest each evening. Getting the dose right week to week is what our weekly pool service is for: we test and balance the water every visit, chemicals included.
Is it safe to swim with high chlorine?
Wait until it is back to 5 ppm or lower. Higher than that is rough on eyes, skin and swimsuits.
Why is the chlorine high in my salt pool?
The cell is making more than the pool is using, which happens in cooler months when the sun and swimmers take less. Turn the output percentage down, or run the cell fewer hours, and test again in a few days.
Can high chlorine affect my pH test?
Yes. Very high chlorine can throw off the pH reagent and give a strange or purple reading. Let the chlorine come down before trusting the pH.
Quick answers
- Will high chlorine hurt my pool?
- A short spike will not. Running high for weeks can fade liners and wear on equipment, and it is a waste of chlorine.
- Can I drain some water to lower chlorine?
- You can, but it is slow and wasteful for chlorine, which drops on its own. Save draining for stabilizer or calcium that is too high.
- Why is my chlorine high but the pool is still green?
- Check that the test reads free chlorine, not total, and check stabilizer. Very high stabilizer holds chlorine back from killing algae.
Sources
Keep reading
How much liquid chlorine should you add to a pool?
To raise free chlorine by 1 ppm in 10,000 gallons, add about 10 fluid ounces of 12.5% liquid chlorine, ab...
How long after shocking a pool can you swim?
Swim once free chlorine has dropped back to 5 ppm or lower and pH is back between 7.2 and 7.8. After a no...
What does pool stabilizer do?
Pool stabilizer, also called cyanuric acid, shields chlorine from the sun so it lasts long enough to keep...
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,...
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