How does a hot tub ozone system work?
Ozone kills bacteria and viruses on contact as water passes through the ozone unit, and it leaves nothing behind in the tub. You still need chlorine or bromine, and you still test. In the One Model, the ClearCore ozone chamber is part of the water-care system.
What does ozone do in a hot tub?
The King County public health hot tub guide (Seattle and King County, Washington) says ozone is an oxidiser that kills bacteria and viruses on contact. It cleans the water that goes through the unit that makes it. Some guides call that unit an ozonator.
The guide points out one limit. Ozone has no residual action. It cleans the water that goes through the unit, and then that clean water goes back into the tub and mixes with the rest. The ozone does not stay in the tub.
Why does an ozone system still need chlorine?
Ozone does not stay in the water. The guide says a tub needs a sanitiser such as chlorine or bromine in addition to the ozone, so that some sanitiser is in the water at all times. The guide's name for what stays in the water is the free chlorine residual: the chlorine still in the water after some has been used up, and the part that is ready to kill germs.
It also says ozone should reduce the amount of the other sanitiser you use, but it cannot replace it entirely. You still run tests of your chlorine or bromine, just as you would with no ozone. The CDC adds that owners must routinely test and adjust chlorine and pH.
How does the One Model use ozone?
The One Model has a ClearCore ozone chamber in the plumbing. Ozone breaks down contaminants as the water passes through it. The chamber is part of the water-care system, along with Active Skim, Waterlab, an antimicrobial filter and the salt system.
The water pump runs 24 hours a day and moves the water through the filter, the ozone chamber, the salt system and the heater. That means the water keeps passing the ozone chamber, and it is always being cleaned and kept warm.
How do the ozone chamber, the filter and the salt system share the work?
Each part has its own job. The ozone chamber breaks down contaminants as the water passes through. The filter traps dirt and debris. Active Skim pulls leaves, hair and oils off the surface. The salt system makes the chlorine that stays in the water.
The King County guide makes a similar point about filters. It says the filter removes most of the dirt and body oils in the water and works with the sanitiser to keep the water clean. No single part does everything, which is why Good Hot Tubs calls it one water-care system.
Does ozone mean you can skip testing?
No. Ozone is one part of the system. Once a week, you test the water with a strip and enter the result in the app. You also check the salt system's run time.
Waterlab reads pH, ORP and temperature in the plumbing, and the app (Gecko in.touch 3) shows them on your phone. ORP is a measure of how well the sanitiser is working. You can check the water before you lift the cover, and the app tells you what the water needs.
What should you ask about any ozone system?
A few questions help when you compare tubs. Ask whether the ozone unit works all the time or during set cycles, what keeps a sanitiser in the water between passes, and how often the ozone part is checked or replaced, and by whom.
For the One Model, the ozone chamber sits on the pump that runs 24 hours a day. Good Hot Tubs has not published how often the ozone chamber is serviced or replaced. Once a year, you book a check-up with your local expert, and that is a fair place to ask.
What does this look like on Vancouver Island?
A local expert on the Island brings the One Model to your yard and looks after it. A One Model is also set up and running on the Island for test soaks, so you can see the tub and ask about the water-care system in person.
Orders open January 1, 2027. Until then, you can answer ten quick questions on the site and ask for a test soak when you send your result.
Questions
Is ozone enough to sanitise a hot tub on its own?
No. The King County guide says ozone leaves no residual in the water, so a tub still needs chlorine or bromine and still needs testing.
Do ozone hot tubs use less chlorine?
The King County guide says ozone should reduce the amount of the other sanitiser you use, but it cannot be substituted entirely.
What is the difference between ozone and chlorine in a hot tub?
Ozone kills on contact as water passes through the ozone unit and leaves nothing behind. Chlorine stays in the water, which is why it is the sanitiser you test.
Does the One Model ozone system run all the time?
The ClearCore ozone chamber is on the water pump, which runs 24 hours a day and moves the water through the filter, the ozone chamber, the salt system and the heater.
Sources
General facts on this page come from these public sources. Facts about the One Model come from Good Hot Tubs.
- Staying Happy and Healthy in Your Hot Tub, sixth edition (PDF). Public Health, Seattle and King County.
- Home Pool and Hot Tub Water Treatment and Testing. U.S. Centers for Disease Control and Prevention (CDC).
Related answers
Is the One Model right for you?
Ten questions about your home and how you would use a hot tub. You see your result before you give any contact details, and you can ask for a test soak on Vancouver Island when you send it.