Too much chlorine in your hot tub: how to bring it down

Poured in too much chlorine? You usually don’t need to drain the tub. Test first, then take the cover off and run the jets, and the level will come down. If it’s very high, swapping some water for fresh water speeds that up. The goal is to get back into range, not below it.

This is general water-care guidance. Your spa’s owner’s manual and your product labels win wherever they differ.

Test before you do anything

A smell is not a reading. CDC says a properly chlorinated hot tub has little odor and that a strong chemical smell indicates a problem, but that problem is often the opposite of too much chlorine. A sharp chlorine smell often comes from chloramines (spent chlorine). Our guide on how to shock a hot tub explains why.

So dip a strip or use a test kit for free chlorine and pH before you change anything.

How high is too high

• CDC’s floor for hot tubs: free chlorine at least 3 ppm. If the reading is above 10 ppm, CDC’s hot tub guidance says to talk to the tub’s operator or owner. At home, that’s you.
• Before anyone gets in: Master Spas’ maintenance guide says that above 5 ppm, bathers should not enter the water until the level comes down.
• Bromine tubs: CDC’s range is 4–8 ppm, with the same talk-to-the-owner advice above 8 ppm.

Let it come down on its own

The Master Spas blog’s first step is time:

1. Take the cover off so the water can air out.
2. Run the jets (and any blower) to circulate the water and help the chlorine break down. Keep the cover open while they run.
3. Don’t add more chlorine. Master Spas says to resist adding more right away, and to wait for the level to settle before you add sanitizer again.

Master Spas also notes that warmer water uses up chlorine faster, so if your spa allows it, a higher temperature can help.

Faster: swap in some fresh water

If the level is very high, Master Spas suggests:

1. Drain a small amount of water, about 6 to 12 inches.
2. Refill with fresh water to dilute it.
3. Run the jets to mix.
4. Retest, and repeat if needed.

Afterward: retest pH and alkalinity

Fresh water and a big chlorine swing can move your balance. Retest pH and total alkalinity once the chlorine is back in range. CDC’s pH range for hot tubs is 7.0–7.8. More in why hot tub pH keeps rising. If the water turned cloudy, see why is my hot tub water cloudy?

Back in range: hold the floor

Lowering chlorine means getting out of overdose territory, not running the tub low. Keep free chlorine at 3 ppm or higher (or bromine 4–8 ppm) whenever the tub is in use, with your own registered product. HealthLink BC advises testing residential hot tub water daily, especially during periods of high use. CDC suggests that public hot tubs check chlorine and pH at least twice a day.

FAQ

What to do next

1. Try Water Match to see whether your fill water runs Soft, Balanced or Hard.
2. Browse all guides.