What’s better for a spa - Chlorine or Bromine? (Common questions, pros and cons of each)

Wondering about whether bromine or chlorine sanitiser is better for your spa? In this article we'll discuss the benefits of each.

chlorine versus bromine

Bromine and chlorine are the two most popular sanitisers used in spa pools and hot tubs around the world.

In this article, we’ll explain the difference between them, highlighting some of the pros and cons of each so you can identify which one is best for you and your family. In general, Spa World® and Spa Store® recommend chlorine over bromine sanitiser.

We cover:

Bromine vs Chlorine health

If used correctly, both bromine and chlorine are safe and approved in most countries to use in moderate levels as a disinfectant in spa pools and hot tubs. However, if the levels of either of these chemicals are too high in your spa, they can cause skin irritation and sore eyes.

If your water is not maintained properly, then there can be traces of ammonia present in your water which can react with bromine sanitiser and produce a gas called bromamines. This has an unpleasant odour and in high concentration can cause shortness of breath, headaches and skin irritation.

Are high bromine levels in my spa dangerous?

Yes they can be. You should always follow the instructions on the chemical label to ensure that you are using the correct dosage.

One of the reasons we prefer to recommend chlorine over straight bromine is because it is fast-acting and dissipates quickly in your spa water. Contrasted with bromine, which hangs around for longer in your spa water.

This means it is quite easy to over-brominate your spa, bringing the levels higher than is safe for bathing and potentially causing damage to your spa components like your heater elements and pump seals.

Bromine levels that are too high can cause red and irritated skin and red eyes. For those with asthma or allergies, bromine can cause a flare-up of symptoms.

If the bromine levels do get too high in your spa, the bromamines which are chemicals released as the sanitiser does its work - these are gases that can be hazardous to breathe in when the levels are too high.

The Canadian federal government has banned the use of bromine in spa pools and hot tubs, because it is easy to overdose a spa with bromine, resulting in unsafe levels.

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What are the advantages of bromine as a spa sanitiser?

  • More stable in warm water than chlorine
  • Can be reactivated with shock and ozone
  • A little more gentle on your skin and eyes than chlorine
  • Less odour
  • Stable supply and pricing
  • Not classified as dangerous goods so easy to ship and store

What are the disadvantages of bromine as a spa sanitiser?

  • Bromine can reduce the pH level in your water making it too acidic and causing corrosion in your components inside your spa - particularly your heater element and pump
  • Bromine is less powerful than chlorine as a sanitizing agent, meaning you need to add more of it to effectively disinfect your water
  • Bromine takes longer to properly sanitise your water and kill all germs
  • Bromine is more expensive than chlorine
  • Bromine breaks down more quickly when exposed to UV light (like sunlight). Many modern spas have a UV sanitizing system built in which can impact the effectiveness of bromine.
  • More maintenance is required. (If you forget to sanitiser or shock regularly with bromine, it will be harder to restore your water)
  • Bromine residue is harder to rinse off your body

What are the advantages of chlorine as a spa sanitiser?

  • Chlorine is a powerful sanitiser and you don’t need to add much
  • Chlorine works quickly to kill bacteria
  • Chlorine is readily available
  • Chlorine is very cost-effective
  • Chlorine is not classified as dangerous goods so it is easy to ship and store
  • It is easy to maintain your spa and keep your water in great condition with chlorine
  • It dissipates quickly so it is not easy to over-chlorinate your water

What are the disadvantages of chlorine as a spa sanitiser?

  • Chlorine can cause skin irritation for some individuals with sensitive skin
  • Chlorine can aggravate those with asthma or upper respiratory conditions
  • If there is ammonia present in your spa water from body oils, lotions, urine, chlorine can react with this releasing chloramine gases which have an unpleasant odour
  • Chlorine does not last as long in the warm water of spas and swim spas
  • If used incorrectly, chlorine can bleach clothing and hair and damage components in your spa

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Is Bromine better for skin than chlorine?

Yes, bromine is slightly softer and gentler on the skin than chlorine, making it a popular choice for those with sensitive skin or allergies to chlorine. Bear in mind however those with sensitivities to chlorine may also experience issues with bromine. They may be better off changing to another sanitiser option like hydrogen peroxide.

man in spa pool

Can I use bromine with a spa ozonator?

Yes. Bromine can be used with a spa ozonator. Although an ozonator is not sufficient on it’s own to sanitise and disinfect your spa water, you may find that you can use less of your sanitiser as the ozonator is helping to kill bacteria and microorganisms in your water.

Chlorine can come in a tablet, granule or liquid form. For use in a spa, the chlorine granules will give the best result.

How long should I wait to use my spa after adding bromine or chlorine?

You should wait 30-45 minutes before entering the spa after adding sanitiser.

The recommended method for adding bromine or chlorine is to dip a bucket of warm water from your spa, then dissolve the sanitiser in the bucket. Turn your jets off then gently pour the bucket into your spa water. Allow the sanitiser to be absorbed into your water before turning your jets back on.

chlorine or bromine

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Can I use chlorine shock with bromine sanitiser

Yes you can, but not at the same time. First shock your spa with chlorine shock, then wait 30-45 minutes for the shock treatment to do it’s work and dissipate from your spa water. You can then add bromine sanitiser as you normally would.

Can I change my spa from bromine to chlorine?

Yes, to change your spa from bromine to chlorine, you will need to drain your spa water, thoroughly clean your spa shell and refill with clean water. Bromine can leave a residue on the surfaces of your spa and inside your pipes plumbing, so it is recommended to run a pipe degreaser through your spa before emptying, then thoroughly clean your spa before refilling and sanitising with chlorine.

You don’t want to switch back and forth between chlorine and bromine. Choose one and stick with it!

Chlorine vs Bromine vs Salt

Another sanitising option for your spa pool is to move to a saltwater system. A saltwater sanitising system uses a process of electrolysis to create a reaction with salt (NaCl) that is dissolved in your spa water. This reaction produces a natural form of chlorine (sodium hypochlorite) which sanitises your spa water.

Read our separate article that explains in more detail everything you need to know about saltwater spa sanitisers.

Bromine Tablets vs granules

If you do decide to use bromine in your spa, you should always use it in the granule form. Bromine tablets in a floating dispenser will not evenly sanitise your water, resulting in some pockets of water in your spa which are over sanitised and others that are not sanitised at all.

This can result in damage to some areas of your spa and plumbing with over sanitising or water that is unsafe due to it not being thoroughly disinfected.

bromine tablet in a floating dispenser

Don't use bromine tablets in a floating dispenser in your spa! These do not sanitise evenly and can damage your spa shell or components.

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Do saltwater spa pools have bromine or create it?

No, saltwater spa pools use a process of electrolysis to convert salt dissolved in water into hypochlorous acid which is a form of chlorine. The chlorine reacts with bacteria in your water to break it down.

You should never use bromine with a saltwater pool as it can react with the chlorine that is formed.

How much Bromine should I use in my spa?

We recommend that you follow the daily dosage recommended on the chemical labels. These recommended dosages have been approved by the APVMA as safe levels to ensure your water is treated effectively to kill bacteria and organisms, while also ensuring that the sanitiser levels do not get too high in your spa water for human comfort and safety.

Can I use bromine and chlorine together in my spa?

No, you cannot mix bromine and chlorine sanitiser together, or interchange back and forth between the two options. Mixing the two chemicals together can result in an exothermic reaction - (heat or even fire!)

What are the alternatives to bromine?

There are products that have a blend of chlorine (sodium dichlor) and bromide salts. This product provides all the benefits of bromine as a sanitiser and the effectiveness of chlorine in one product. These two products are the Spa Store Chlorine and BioGuard Armour.

Note that the bromide salts are in a different state to bromine sanitiser, so there is no danger of a reaction between chlorine and the bromide salts.

The chlorine component of these products acts quickly and powerfully to oxidise bacteria and organic matter in your spa water. When the chlorine has finished disinfecting your spa water, it dissipates quickly.

The bromide salts are longer-lasting in warmer temperatures and stay in your water in an inactive form and are re-activated by ozone.

These products offer the best of both worlds with the power and efficiency of chlorine and the long-lasting effectiveness of bromine.

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What is ionising vs oxidising

Oxidising is the process that chlorine uses to kill bacteria in water. When chlorine is added to water it forms hypochlorous acid, which attacks bacteria cell walls, breaking them down.

Bromine sanitises your spa water by ionising bacteria. This process changes the chemical formation of bacteria and microorganisms, breaking them down by forcing apart the chemical bonds that hold them together.

Can I use bromine with Nature 2 Spa minerals?

No you cannot use bromine with the Nature 2 Spa system. Bromine will react with the silver ions inactivating them so they won’t operate properly to sanitise your water. In addition, you may find a sticky residue forming around the Nature 2 Spa stick and cloudiness in your water.


Hopefully, by now you have a clear understanding of the difference between chlorine and bromine spa sanitiser, enabling you to make an informed decision on which is best for you and your family.

Got more questions?

Talk to us on live chat, or email us your spa chemical questions and we'll be happy to help!

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