3 Ways to Lower Chlorine or Bromine in Your Hot Tub (Naturally & Chemically)

There have been many times over the years that I’ve added too much sanitizer to my hot tub. Here is what I’ve learned about how best to lower the levels of chlorine and bromine.

Chlorine and bromine levels can be lowered naturally by allowing the sanitizer to break down for 24 – 48 hours. An alternative method for naturally lowering sanitizer levels is to dilute the hot tub with fresh water. The fastest way to reduce or remove sanitizer is to add a chemical called sodium thiosulfate.

A strong chlorine smell from a hot tub is not a sign of high chlorine levels. The strong odor people typically associate with excess chlorine is actually caused by chloramines.

If you suspect the levels are too high, always test to confirm your suspicions first. Here is a table showing the recommended safe levels.

SanitizerAcceptable rangeOptimum level
Chlorine1 – 3 ppm3 ppm
Bromine3 – 5 ppm5 ppm

1. Use a neutralizer product

If you need to use your hot tub right away, the fastest way to lower chlorine or bromine levels is to add a neutralizerOpens in a new tab. product.

Neutralizer contains sodium thiosulfate, which is an inorganic sodium salt made up of sodium and thiosulfate ions in a 2:1 ratio.

Sodium thiosulfate removes free and combined chlorine (and bromine) from spa water. Using sodium thiosulfate is the preferred option as it’s deemed to be the safest.

It’s easy to use and one of the most cost-effective ways to reduce sanitizer levels in hot tubs. However, care does need to be taken not to overdose the spa when using neutralizer.

If you overdose, you’ll likely experience difficulty in trying to raise the chlorine or bromine level back up. This is only temporary, however, as the sodium thiosulfate will dissipate within a few days.

Start by adding a small amount, allow it to circulate, and then test. Remember to also test the pH after adding neutralizer as it can cause slight fluctuations.

The dosage may vary slightly depending on the manufacturer, so follow the instructions listed on the bottle.

2. Lower chlorine or bromine naturally

The easiest way to lower excess levels of chlorine or bromine sanitizer in your hot tub is to do so naturally without the use of chemicals.

As long as you’re not in a rush, being patient over the course of one to two days is all that is required as the available free chlorine or bromine gets broken down naturally by sanitizing all the impurities in the water.

Removing the cover and turning on the jets speeds up the rate at which the sanitizer dissipates by way of evaporation. Take advantage if it’s sunny as the ultraviolet light will naturally destroy the chlorine or bromine in the water.

Never use a hot tub when it contains too much chlorine as it can cause irritation to the skin and eyes. In extreme circumstances, it can affect breathing too.

3. Dilute the spa water

If you’re not able to wait around for a couple of days for the sanitizer levels to lower naturally, you can speed up the process significantly by diluting with fresh water.

Start by using test strips to test the chlorine or bromine levels in the water to give you an idea of how much you’ll need to remove.

Grab a clean bucket and remove as much as you think is necessary. Don’t worry about removing too much water.

It’s better to remove more than you think is necessary as topping up with chlorine or bromine is easy to do afterward.

Do not dispose of the spa water onto your lawn as the high sanitizer levels may damage and kill the grass, plants, and surrounding vegetation.

Empty the buckets into the sanitary sewer in your yard. Alternatively, you can get rid of the spa water by pouring it down the drain in your home’s sink, bathtub, or toilet.

Once you’ve removed enough, refill with fresh water from a garden hose fitted with an inline pre-filter. Run the jets to allow the water to circulate and perform another test.

In extreme circumstances, you may need to completely drain your hot tub in order to lower the sanitizer level enough so that it’s safe.

Can I use hydrogen peroxide to lower chlorine or bromine in my hot tub?

Hydrogen peroxide (H2O2) is a chemical compound commonly used in pools for its powerful oxidizing, bleaching, and disinfectant properties. But is it useful for lowering chlorine?

Hydrogen peroxide can be used to lower chlorine and bromine sanitizer in a hot tub. Hydrogen peroxide is a powerful oxidizer that breaks down the sanitizer through chemical reactions. However, the high concentration levels needed to neutralize chlorine makes it very dangerous. Improper handling can result in burns and blindness.

Hydrogen peroxide cannot exist alongside chlorine or bromine in water, which is why it’s sometimes used as an inexpensive way to remove chlorine from swimming pools and spas.

But the hydrogen peroxide used to treat pools and hot tubs isn’t the same strength as the three percent solution used to treat cuts and wounds that you’ll find in plain brown bottles at the drugstore.

Hydrogen peroxide used to sanitize pools and hot tubs is typically a 35 percent concentrate. This high concentrate is also known as pool-grade or food-grade hydrogen peroxide.

At such high concentrations, hydrogen peroxide is highly dangerous. Extreme care needs to be taken during transportation, storage, and handling. As well as being an inhalation hazard, it can cause blindness, severe burns, and even fire.

Another issue with using hydrogen peroxide is that adjustments have to be made to the water chemistry beforehand. Hydrogen peroxide naturally lowers pH levels, which need to be raised as the chemical is no longer effective if the pH falls below 7.0.

Due to the risks involved and how it plays havoc with the pH, I don’t recommend using hydrogen peroxide to lower chlorine or bromine levels in your hot tub. Neutralizer is easier to use and far safer.


Is it safe to go in a hot tub with high chlorine?

It’s not safe to use a hot tub with high levels of chlorine. Chlorine levels above 3 ppm can result in irritation to the eyes, skin, and lungs. Inhaling chlorine vapor can also aggravate asthma symptoms and increase respiratory problems. Excess chlorine makes the water more acidic, which causes corrosion in the hot tub.

What do I do if I over shock my hot tub?

If you add too much shock to your hot tub, the easiest thing to do is wait 24 – 48 hours for the chlorine levels to lower naturally. Removing the cover causes evaporation, speeding up the rate at which the chlorine level reduces. You can add sodium thiosulfate (neutralizerOpens in a new tab.) to rapidly lower chlorine levels.

How long does it take to reduce chlorine or bromine in a hot tub?

It takes between 24 – 48 hours for excess chlorine or bromine levels to lower to a safe level. Chlorine and bromine levels naturally break down over time as they sanitize impurities in the spa water. Turning on the jets, removing the cover to allow for evaporation, and diluting with fresh water can speed up the process.

Joshua Milton

Joshua Milton is a seasoned hot tub enthusiast. With many years of experience in the industry, he offers valuable insights on hot tub maintenance, health benefits, and relaxation techniques.

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