Bromine and chlorine are the two most common hot tub sanitizers. They help you to kill bacteria, clean up skin cells and soap residue. But which one is better? And if both of them are good, is mixing bromine and chlorine in hot tub a good idea? We’ll help you to find out.

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A quick look at Chlorine and Bromine

Chlorine oxidizes contaminants by invading them and destroying them from the inside out, while bromine ionizes contaminants by forcing apart their chemical bonds. When chlorine works, it turns into a waste product called chloramines whereas bromine produces bromamines.

Chlorine dissipates in water more quickly than bromine, but bromine is more stable than chlorine, especially in warm water. Bromine kills bacteria in your spa for a longer period of time than chlorine.

While chlorine can be harsh on the skin, hair, and eyes, especially at high levels, bromine is gentler on your skin but can be more difficult to wash off after a long soak.

Chlorine is available in three formats: granules, liquid, and tablets. The granules or liquid are both easy to use, users can add them directly into the water without using any specialized equipment. If you use the tablets, you will need a floating feeder to ensure a balanced level of chlorine in the water.

Using bromine is quite similar,  to maintain bromide levels, users will also need floating feeders.

Can I use a Chlorine shock with bromine?


Yes, you can. Shocking a bromine pool with non-chlorine shock or with chlorine shock is fine. As long as you make sure to avoid mixing the chlorine and bromine in their powdered form, you won’t face any problems. However, adding chlorine shock will raise the chlorine level in your hot tub, so it’s best to test the water before entering.

Is it safe when switching from chlorine to bromine and vice versa?

If you follow the right process, switching from chlorine to bromine in your hot tub is fine. However, it’s important to note that you should not add chlorine in the water that has bromine and vice versa.

Chlorine activates bromine in water, which means bromine will take a long time to dissipate completely, and can potentially become dangerous. Therefore, it’s best to drain the pool water to remove the build-up of bromide ions.

The process is quite simple: drain the water with chlorine inside, clean your hot tub thoroughly, then fill the hot tub with fresh water and add your bromine.

If you do not have time for the draining, cleaning, and refilling steps, you can choose to use bromine tablets from the beginning, instead of using chlorine. It’s a non-chlorine option that is popular for indoor hot tub use.

Bromine does not produce irritating odors as chlorine does, and it is also safer for your health. More importantly, it’s also extremely effective in temperatures of 75°F, making it a great choice for hot tubs and spas.

Pay attention when mixing bromine and chlorine in hot tub


Some hot tub suppliers recommend their customers mix chlorine and bromine together, which can increase their sales. However, before following their suggestions, one should ask: What happens if you mix bromine and chlorine in a hot tub?

Mixing them together in the water can cause a dangerous chemical reaction. The chlorine and bromine mixture can produce a cancer-causing liquid, which is only a bit less dangerous than highly radioactive liquids.

Bromine and chlorine reaction creates about 97 carcinogens (a substance that promotes carcinogenesis – the formation of cancer), 82 mutagens (another form of carcinogens), 28 toxic contaminants, and up to 23 tumor promoters. These chemicals stay permanently in the bathers’ body fat and increase the risks of cancer.

Every time our body is exposed to these chemicals, there’re the risks of getting this life-threatening disease increase. The more exposure, the higher the risks are. Given this, never mix chlorine and bromine together or mix one of them with other chemicals.

In case you need to change chemicals in your hot tub, it’s best to empty it first and start with setting the pH level correctly. Making sure that your spa water has the right level of pH is important. If it is not balanced, the water could negatively affect your tub.

A balanced pH level is the right balance of acidity and alkalinity. Too acidic water might corrode your hot tub equipment, cause etching on the surface materials, and skin, eye, or nose irritations for swimmers.

The level of pH for the hot tub should be between 7.2 – 7.8, the ideal level is 7.4. Too high or too low a level of pH can cause issues for hot tubs and bathers. When your alkalinity is too high, it could be a sign of extremely calcium-rich water or other issues. Also, the pH level needs to be checked once a week by using tester strips.

Safe tips on adding chemicals to hot tubs

Smelly and cloudy hot tub water is one of the biggest challenges of hot tub owners. Given this, they should be regularly maintained and sanitized to reduce the risks of developing hot tub rash and other bacteria.

After cleaning the filters by using vinegar or other homemade mixtures, you can refill the spa and heat it to your desired temperature. Then, test the pH level and alkalinity level of the water and adjust it accordingly, then retest both of them again to make sure they’re in proper ranges.

After having the right level of pH and alkalinity, you can sanitize it with bromine or chlorine. The recommended range is 3-5mg/l and the addition of these chemicals will depend on usage and bathing habits. Hot tub owners are also recommended to shock the water once a week to control bacteria growth and destroy the impurities.

In a nutshell

Mixing bromine and chlorine in hot tub should not be done as the combination of these two chemicals can cause serious health risks. Before thinking about using either bromine or chlorine for your hot tubs, it’s best to keep the right levels of pH and alkalinity for them.

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