How To Lower Chlorine Or Bromine In A Hot Tub (If Too High)



Both chlorine and bromine are effective sanitizers for your hot tub, providing bathers protection from viruses, bacteria, and pathogens.

The ideal level of chlorine in a hot tub is between 1 and 3 ppm (parts per million), with bromine’s ideal level ranging from 3 to 5 ppm. If these levels peak past these ranges, your water chemistry can become compromised.

Let’s talk about why this happens, why it matters, and how to lower chlorine or bromine in your hot tub.

Why Your Chlorine Or Bromine Level Is High

To start, how do you decide which is a better sanitizer for your tub?

Bromine is commonly used because it excels in high water temperatures (anything over 75°F), whereas chlorine is better for anything under 65°F. 

However, if your spa is open to sunlight, chlorine is the option to go with. This is because the sun’s UV rays destroy bromine and chlorine within a matter of hours. 

But if you use chlorine, you can add cyanuric acid (CYA) to stabilize and protect the chlorine from sunlight degradation. 

This is not so for bromine, as there’s no stabilizing chemical that can protect it from the sun. For this reason, shaded or indoor spas usually use bromine, while tubs in the sun use chlorine with CYA.

For any sanitizer to be effective, the right amount must be present in the water at all times. 

High levels of either chlorine or bromine usually occur when you’ve overdosed the tub with them. This can be the result of adding too much sanitizer (by accident) during regular maintenance, or it could be from shocking the water. 

When you shock a hot tub you’re adding a massive dose of chlorine shock (for chlorine tubs), or non-chlorine shock (for bromine tubs). Shocking is done to quickly kill off everything in the water. For a period of time, the sanitizer will remain at this heightened level because of it.

Why High Chlorine Or Bromine Is Bad News

When chlorine or bromine levels are too high for extended periods of time, it can cause all sorts of issues with your water.

  • Pungent water. You know that pungent chlorine smell some hot tubs get? It’s not lack of chlorine in the water, but actually a sign that there’s not enough of it. Chlorine and bromine both off-gas as they’re used up. When these gasses accumulate, the water becomes pungent with chloramines and bromamines. This gas can irritant swimmers lungs and even cause respiratory distress.
  • Health issues. Overly high chlorine or bromine levels can cause issues with your health. Itchy skin, brittle hair, red and irritated eyes, and irritated nasal passages are all signs you have too much sanitizer in your tub.
  • Damage to your tub. High levels of chlorine or bromine will slowly eat away at the soft surfaces in your tub, and may even cause a leak. Buildup under your hot tub cover can also occur.
  • Equipment can be compromised. Not only will problems arise with the tub itself, but the equipment you’re using to run the tub can be damaged. With too much sanitizer, it will corrode plastics like your plumbing, the pump, and even the filter. Additionally, it can also ruin your hot tub heater. These are all major components that many times can’t be salvaged.
  • Decreased pH level. With spiked levels of sanitizer, the pH level of the water will drop. When this happens the water turns acidic, and you’ll have to spend more time and money returning the water chemistry to a neutral state.

How To Lower The Sanitizer Level In A Hot Tub

So you have problems with high chlorine or bromine and you need to fix it fast. 

Lucky for you there are a few solutions and none of them are very difficult.

Option #1: Wait It Out

Simply put, just wait. Do nothing to the water. 

Forget about adding any more doses of your sanitizer, and if you’re using an automatic chlorinator, shut it off.

By doing nothing you’re ensuring you’re not adding to the already spiked level of chlorine/bromine. It will naturally come down after a day or two. 

Be sure to stay out of the tub during this process, as the high levels can cause irritation to bathers, and if you use a hot tub cover, remove it while waiting.

With the spa uncovered, it allows for the water and sanitizer to naturally evaporate, which will speed up the process.

Option #2: Drain And Dilute

Your second option is to partially drain the hot tub and then dilute it by refilling it with fresh water. 

If you’re waiting it out, the water level will eventually drop (evaporation) and you can just add clean water to the tub. However, if you want to speed things up, follow the steps below. 

Additionally, if you haven’t swapped the water in the tub for 2 or 3 months, or you’re finding the water is having a ton of issues staying balanced, a drain needs to be done.

Here’s how to do it:

  1. First things first, turn off the tub. Never drain while the tub is still connected to an electrical outlet (for obvious reasons).
  2. Remove the drain plug at the base of the hot tub and attach a hose to it. Ensure that the hose is long enough to reach an area where it’s safe to dump wastewater. Let the tub drain, either partially or fully.
  3. Another method of draining is by using a submersible pump. Attach a hose to the pump, place the pump in the tub, and connect the pump’s power cord to an electrical outlet. Turn on the pump and let the water drain. If doing a full drain, keep an eye on the water level so the pump isn’t running in an empty tub. This can burn out the motor.
  4. While the tub is draining (full drain takes a few hours), clean out the filter. Sand filters and DE filters should be backwashed and rinsed. For cartridge filters (the most common for hot tubs), remove the cartridge and hose it down until it’s free of debris. If it’s very dirty, you can do a chemical soak using a vinegar and water solution, or using a cartridge cleaning product. Once it’s clean, rinse it thoroughly and put the filter back together.
  5. If doing a partial drain, skip this step. With the hot tub now empty (full drain), give it a good cleaning. Soap, warm water, and a soft cloth work well, although you can use a spa cleaning product if you wish. Rinse the tub thoroughly.
  6. Fill up the hot tub with fresh water from your outdoor spigot.
  7. Test the water with strips or a testing kit and record the levels for pH, total alkalinity, and calcium hardness.
  8. Add in the necessary chemicals to properly balance the water. pH should be between 7.4 and 7.6, TA between 80 and 120 ppm, calcium hardness between 175 and 250 ppm, and chlorine between 1 and 3 ppm (or bromine at 3 to 5 ppm).

Option #3: Neutralize It

If you’re in a hurry to drop the sanitizer level, a third option is to use Chlorine Neutralizer.

This product is made from sodium thiosulfate and works by reducing the free available chlorine level in the water (it will also do the same with bromine).

However, the problem with using neutralizer is that it will continue reducing the level of chlorine/bromine until all the neutralizer is used up. Basically, you can end up removing too much sanitizer from the water, so use it conservatively.

Here’s how to do it:

  1. Test the water to find out the sanitizer’s current level. 
  2. Calculate how much (in ppm) you need to drop the chlorine/bromine.
  3. Consult the directions on the bottle for proper dosage. Be very careful with your math here. It’s easy to overdose with neutralizer, and it will wipe out all your chlorine/bromine if you’re not careful.
  4. Measure out the amount of neutralizer and pour it into the hot tub.
  5. Run the jets for about an hour to circulate the chemical.
  6. Retest the water and make any necessary adjustments.

What Goes Up…

The bad news is that your chlorine or bromine levels may one day get too high and cause a slight panic. 

The good news is you can easily lower the chlorine/bromine in your hot tub by simply being patient, diluting the water, or using a chemical neutralizer. 

After all, what goes up must come down!

Categories: Hot Tub Care, Hot Tub Chemistry