When it comes to hot tub sanitisers, there are two main options: chlorine and bromine. Both are commonly used, and there’s lots of opinions out there on which is best for your hot tub.

So how do you know which is right for you? The truth is there are pros and cons to each. However, bromine is generally easier to manage, so if you’re new to having a hot tub, it’s usually the best choice.

But, if you’re an experienced hot tub owner, or you want to really dig into the pros and cons of each, read on to find out everything you need to know. At BMS Spas, we’re experts in everything about hot tubs, so we’ve summarised the key info to make it easy for you to make the right decision.

Why do you need a hot tub sanitiser?

It’s essential to keep the water in your hot tub clean and bacteria free. If you ignore this important aspect of hot tub maintenance, you could damage your hot tub or even affect your health – it’s vital stuff.

Because the water in your hot tub is kept warm, it’s at a perfect temperature for dangerous bacteria, algae or mould to grow. Plus, as you use your hot tub, your body naturally deposits trace amounts of waste like skin particles and other contaminants.

To keep your hot tub clean and remove these contaminants, you’ll need to use a sanitiser. Bromine and chlorine are by far the most popular choices, with the vast majority of hot tub owners using one of these two options.

Chlorine and bromine: what’s the difference?

Both chlorine and bromine are effective sanitisers for hot tubs. In short, they’ll both do the job. But there are some key differences in the way the two work and the way you’ll need to use them to clean your hot tub.

Chemical changes

The first difference is in the way that the two sanitisers work chemically. Without digging too much into the details – chlorine oxidises contaminants, turning them into chloramines, while bromine ionises them, turning them into bromamines. The process is very similar, but the chloramines produced by chlorine are typically chemically harsher than bromamines, causing that stinging effect you often get in swimming pools.

Speed of use

Another difference is in the speed that each chemical cleans your pool. Chlorine will clean more quickly than bromine. However, it also dissipates more quickly, so you’ll end up replacing it more often. In general, bromine is a better solution for regular cleaning, as there’s less work involved in redosing your hot tub.

Warming up

Bromine tolerates heat much better than chlorine does. This alone makes it a better option for hot tubs. What this means for you is that bromine will generally last longer in hot tubs. Chlorine will typically dissipate quickly, so you’ll end up topping up your hot tub more often.

Health benefits

Both bromine and chlorine are safe to use as a hot tub sanitiser, so long as you keep to the proper dosages and amounts – more on that shortly. But, chlorine can sometimes be harsher than bromine, particularly on your skin or eyes. If you, or one of your hot tub guests, has sensitive skin or a respiratory illness like asthma, it’s usually better to stick with bromine.

Getting your doses right

Whichever sanitiser you choose, you need to make sure you’re using the right amounts of each at the right times. Firstly, follow all the manufacturer’s instructions for filling the pool and adding sanitiser and other cleaning solutions. It’s essential that you understand what products you’re putting into your hot tub, as things can sometimes react poorly with each other.


You’ll need to test your water to make sure that you’ve got the sanitiser levels correct. There’s lots of ways to do this, so choose whichever you prefer. Getting a frequent, accurate reading is crucial.

The right levels

The actual level in terms of parts per million varies with each sanitiser. For chlorine, you’ll want to aim for 1-3ppm, and for bromine, it’s 3-5ppm.

Tablets or granules?

Both chlorine and bromine are available in either granules or tablet form. You can choose either as it doesn’t affect the way the sanitiser functions. However, it does affect how often you need to add the sanitiser to your hot tub, and the process.

Granules are simply poured into your hot tub, while tablets are added to a feeder, which will slowly release the chemicals over time. In general, tablets are an easier option, especially if you’re not using your hot tub multiple times per week. If you’re a heavy hot tub user, you might prefer to use granules as it’s easier to manage a frequent cleaning process.

Can you switch from one to the other?

In short, yes! If you choose one sanitiser and you don’t like it, you can switch. However, you should be careful as the two chemicals can react badly with each other if they’re both added to the same hot tub. It’s best to wait until you drain your hot tub and completely replace the water to switch sanitisers. Be careful to clean out filters or feeders, too, as trace elements of the chemicals can react with each other.

Bromine vs. Chlorine: which is best?

So, to sum up – is bromine or chlorine right for you? Here’s a quick list of the pros and cons of each to make it easy for you to decide.



  • Works better at higher temperatures
  • Lasts longer so less frequent redosing
  • Less harsh on skin or eyes



  • Can be more expensive
  • Works slower so can be tricky to manage if you use your hot tub a lot




  • Cheaper than bromine
  • Works quickly
  • Dissipates more quickly



  • Doesn’t last as long so may need more frequent use
  • Can be harsh on sensitive skin


It’s up to you which sanitiser you choose for your hot tub. For many people, bromine is a better choice, but there are still people who prefer to use chlorine.

Alongside a sanitiser, you’ll also need to clean your hot tub regularly. Check out our guide on the whole process of hot tub cleaning.

Let the professionals decide

Don’t fancy making all these decisions and worrying about your hot tub cleaning? At BMS Spas, our experienced team can carry out regular cleaning and service visits, and we’ll give you our advice on which sanitiser is best for you. We can explain the whole process and let you know how to test your water and which sanitiser to use.

Get in touch with us to chat about our service options for your hot tub.