What is ozone in a spa pool? (Do I need it?)

If you have been researching spas, you will probably have come across the term Ozone. Ozone automatic sanitiser (or oxidizer) systems have been around in spas for almost as long as spas have been around.

An ozone system helps to keep your water clean and clear without the need for so many chemicals. In this article Spa World CEO, Andrew Pullen, explains how ozone works and what he thinks of it.

In the spirit for transparency, until recently, I thought ozone systems in spas were overrated, but I have recently changed my mind.

One of the perks of being the CEO of the world’s largest spa retail group is that I get to ‘test’ a lot of different spa pools. The most recent spa I have been using was delivered (mistakenly) without an ozone unit fitted and boy did I notice the difference!

Not only have I been using more chemical sanitiser to keep the spa’s water clean and clear, but try as I might, I can’t get the water quite as clear as in my previous spas. And this is not because my current spa has an inferior filtration system. Quite the opposite, it has the latest and greatest.

So through personal experience, I have become an advocate for ozone sanitisers in spas.

"Through personal experience, I have become an advocate for ozone sanitisers in spas."
Andrew Pullen – CEO, Spa World™

How does ozone work in a spa and what does ozone do?

An ozone generator converts Oxygen (O2) from the atmosphere, into Ozone (O3) in your spa. (O3) means that there are now 3 Oxygen molecules. Oxygen is an Oxidiser and when (O3) comes into contact with microscopic particles in the spa water, it dissolves those particles.

There are two technologies that are used to generate (O3). UV (not to be confused with UV sterilizers, which simulates the effects of sunshine), and Corona Discharge, which simulates the effects of lightning!

The Corona Discharge system is thought to be the best and most spa manufacturers now use this technology.

Ozone is an oxidiser, just like Chlorine, Bromine, and Hydrogen Peroxide, the three most common spa chemical sanitisers. Because ozone works the same way, it means you use less of these chemicals.

Oxidisers make various contaminants in your spa’s water ‘inert’ so that they can be removed by the filter system. In doing so, they make the water not only cleaner, but also safer as they kill nasty bugs.

It is worth noting that Ozone will not replace the need for some chemical sanitizers, it simply reduces the amount you need to use.

"Ozone will not replace the need for some chemical sanitizers, it simply reduces the amount you need to use."
Andrew Pullen – CEO, Spa World™

Is Ozone in a spa pool harmful to humans?

Not in the concentrations used in a spa pool. This is a technology that has been around for decades and there is no evidence of harmful impacts on spas users. In this way, it is no different from the above chemical sanitisers. Safe to use in your spa but you wouldn’t want to drink them!

Can Ozone damage a spa pool?

Yes, if used incorrectly. Any oxidisers can damage the plastic components, shell, headrests and cover of a spa in concentrations that are too high. As such, Ozone systems must be installed in spas in a certain may. I have seen many poor quality spas destroyed over the years as inexperienced manufacturers fit Ozone units incorrectly.

Does the Ozone unit require maintenance and how much does it cost to replace in a spa?

Ozone units have to be replaced roughly every 5 years. They range in cost from $200-300. Not a huge amount for a component that offers so much value to your overall ownership experience.

Are there other automatic cleaning systems for spa pools?

Yes, you can purchase spa pools with UV sterilisers, multistage filter systems, spa chemical dispensers, and salt chlorinators. You see our separate articles on these systems.

A point to note with salt water chlorination systems. They still use chlorine. They are simply a system that converts the chlorine in salt to chlorine in the water. If you wish to avoid chlorine, there are a number of non-chlorine sanitizers available without the need to invest in an expensive saltwater chlorination system.

"At Spa World, we believe in Ozone so much that every spa we carry is fitted with an Ozone sanitising system."
Andrew Pullen – CEO, Spa World™


I recommend that every spa should have an Ozone unit installed. Fortunately, they are standard on most high-quality spa pools. On very cheap plug and play spas they are often optional and it is one option I would say is a must.

At Spa World, we believe in Ozone so much that every spa we carry is fitted with an Ozone sanitising system.

If you wish to learn more about Ozone systems, a Spa World Spa Specialist can help you with your questions. Educate yourself on what to look for with the Ultimate Spa Buyers Guide.

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