Bromine vs. chlorine – the age old hot tub water debate

From the beginning of spa care, there has been great discussions about what sanitizer is better – bromine vs. chlorine? Like all things in life there are pros and cons for each and the answer is this – it depends on the hot tub and the spa owner.

What is the best sanitizer type for your hot tub – granules or tablets?

The first step to deciding what sanitizer to use has nothing to do with bromine or chlorine at all – I has to do with your choice of how to dispense your sanitizer. Do you prefer adding a little bit of granular product before and after each use and as needed to maintain a safe and healthy sanitizer reading on your test kit of 3-5 ppm? Or do you prefer to fill a floating (or built in) dispenser with tablets and adjust the application rate as needed. Why should you decide this first? All your chemistry decisions in your hot tub have side effects – both good ones and challenges. Be narrowing down the most convenient way to sanitize the hot tub for your lifestyle, it will help decide if bromine or chlorine is most suited to your lifestyle and budget.

If granular sanitizer works best for you…

Bromine, all the way. Brominating Granules kill bacteria with the least effect on the rest of your water balance. They are effective even if your spa water ph bounces. They have a low dosage so your money goes a long way. The only drawback is that you do have to test your water frequently and apply as much or as little as it takes to consistently keep your bromine residual above 3 ppm (and below 5 ppm).

If slow release tablets will work best for you…

If you decide that a slow release tablet to add a small dose of sanitizer for you as they dissolve will be best for your lifestyle, then there are some considerations. The first and most important thing with either bromine or chlorine is to ensure you are using HOT TUB FORMULATION PRODUCT! Pool and hot tub chemicals are vastly different in the sanitizer category and to use a pool product in your hot tub can cause ireparable damage.

Is ph and important consideration in bromine vs. chlorine for my hot tub?

You should. Proper pH in your spa is difficult to achieve and will dictate your bather comfort as well as how long yoru equipemt will last. When your pH fluctuates, your sanitzer effectiveness can change. Bromine is most resistant to this change but bromine tables tend to pull ph down as the water ages more so than chlorine does. It is a bit of a chicken and egg issue. Chlorine tablets tend to perform best if your source water has low ph and total alkalinity or if you run your spa in the winter months and are unable to drain and refill your water every 6-8 weeks.

How do you shock a chlorine vs. bromine spa?

When deciding on chlorine or bromine tablets you should also consider how much you shock/oxidize your water. Bromine tablets perform best when there is frequent oxidation taking place. Chorine is much more forgiving that if you forget to shock one week, your sanitizer costs are not likely to measurable increase.

What makes the most ‘cents’ bromine vs. chlorine?

Technically speaking, chlorine is a ‘stronger’ sanitizer than bromine and therefore you will likely use less chlorine than bromine. Chlorine also tends to cost less per gram than bromine does so it is a wonderful sanitizer to suit keep your wallet happy.


To bring it all together, what is the best sanitizer for your hot tub – bromine vs. chlorine? The easy answer is to work with your local hot tub professional. Have a professional spa water test done. Spend some time discussing all the unique aspects of you and your hot tub and put together a plan.  This way you will be educated on all the positives and the challenges.  Any hey, if you don’t like your choice, just drain your hot tub and try an alternative…simple and easy…that’s what spa care is.


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