Is Chlorine or Bromine Better for a Hot Tub With an Ozonator?

Jennifer Rhodes

By Jennifer Rhodes · Updated

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Are you wondering which sanitizer is best for your hot tub if you have an ozonator? You've heard of both chlorine and bromine, but are not sure what the difference is—or which one you should use.

The difference comes down to one main factor: bather load. If you have a high bather load (e.g. you use the spa daily, or in large groups) you can use either chlorine or bromine. If not, bromine is the better choice.

Keep reading to find out why, and learn which sanitizer is ultimately going to be best for your hot tub, plus a few pros and cons of both chlorine and bromine.

What is the role of ozone in hot tub sanitation?

We all want our hot tubs to be clean and safe, right? But with repeated use, germs, dirt, and other contaminants can build up, leaving them anything but hygienic. But don't worry, the ozone in a hot tub with a ozonator can help to keep it clean.

The general idea is that adding an ozonator to a spa can actually increase the amount of sanitization your spa receives.

Ozone acts as an oxidizer, breaking down contaminants in addition to your usual sanitizer.

By providing additional oxidation, an ozonator should help make your sanitizer more effective by destroying bacteria and other contaminants, reducing the amount of sanitizing chemical needed while still keeping the spa sanitized.

When it comes to hot tub sanitation, an ozonator plus sanitizer is a popular and effective combination. It helps keep your hot tub clean and hygienic, and helps to reduce any unpleasant substances.

Using chlorine in a spa with an ozonator

Chlorine is considered the go-to for most spas and pools. It is recommended by health and environmental experts as the most cost-effective and reliable sanitizer. Plus, it works fast and is easy to maintain.

However, chlorine does have its drawbacks when combined with ozone. If you have a low bather load, meaning not enough contaminants to keep the ozone busy, ozone can actually start to oxidize the free chlorine in a chlorine spa (which is bad because then you have less sanitizer!).

But if you have a high bather load, then there's more likely to be plenty of contaminants to kill. In this case, combining chlorine with ozone can be a great way to maintain a healthy and comfortable spa environment.

Using bromine in a spa with an ozonator

Chlorine is the most common sanitizer used in hot tubs, but it isn't your only option. Bromine, especially when paired with an ozonator, is a powerful duo when it comes to keeping your hot tub clean, clear and free of bacteria.

Let's consider what advantages bromine brings to the table. Unlike chlorine, bromine is not affected by ozone when they are used together. This means that while ozone can sometimes oxidize free chlorine (making it less effective), bromine is able to maintain its effectiveness.

On top of that, bromine will benefit from ozone's strong oxidization properties. Together they form a powerful team, better able to fight against bacteria, algae, and other pollutants, giving your hot tub a sparkling clean boost.

Chlorine vs bromine: other factors to consider

When it comes to choosing a sanitizer for your hot tub with an ozonator, let's take a look at some of the key factors you should consider before making a decision.

Bather Load

The number of bathers using the hot tub is one of the most important deciding factors:

  • If you have a lower bather load, bromine would be the best option for you. Unlike chlorine, it maintains its full effectiveness when combined with an ozonator, as the ozone cannot lower its levels.
  • If you have a larger bather load and/or more frequent use, chlorine may be a better choice. It's generally considered the more effective sanitizer overall, and can even keep your spa water clean for longer between drain-and-refills.


It's also important to consider the cost of each sanitizer. Generally, chlorine is the more affordable option, but the cost of bromine has come down significantly in recent years.


Another factor to consider is how much maintenance each sanitizer requires. Chlorine requires more maintenance, as it has to be added regularly to maintain the desired level of sanitization. Bromine, on the other hand, can go for longer periods without needing to be topped up.

I also have more detailed guides on how to use bromine or chlorine in your spa, based on my experience over the years.

Closing thoughts

So, there you have it! We’ve just taken a look at the two main ways to sanitize your hot tub with an ozonator: bromine and chlorine.

While chlorine is usually the more commonly used option in general, it's only a good idea to combine chlorine with ozone if you have a high bather load. Otherwise, why not pair bromine with your ozonator in your hot tub? This way, you get the powerful cleaning benefits of both, without the worry of one affecting the other. That's a win-win all day long!

Ultimately though, the choice between chlorine and bromine will come down to your specific hot tub setup and needs. Consider all of the factors above carefully before making your decision.

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