What Are Hot Tub Ozonators And How Do They Work?



Chemicals like chlorine and bromine are the traditional sanitizers you’ll find in most hot tubs, but there are alternatives that can be used to further treat the water.

Hot tub ozonators are one of them. This device hooks up to your tub to help keep the water cleaner than if you were to only use chlorine or bromine.

Let’s explore ozonators in detail so we can determine if they would be a good addition to your spa.

What Is Ozone?

Isn’t ozone that thing in the atmosphere with a big hole in it?

Well, yes — but when talking about ozone and hot tubs, we’re referring to using an ozone generator as a powerful disinfectant and oxidizer.

It does this by generating ozone gas and injecting it into the hot tub’s water.

This process helps remove all kinds of pollutants in the water (bacteria, viruses and pathogens), improving the water quality while simultaneously reducing the amount of sanitizer that is needed to keep the tub clean.

Why Use Ozone In Hot Tubs?

Should you invest in a hot tub ozonator? Here are a few reasons that may convince you:

  • You’ll use less sanitizing chemicals. The ideal level for chlorine in hot tub water is between 1 and 3 parts per million (ppm), or between 3 and 5 ppm for bromine. With an ozonator, you won’t need nearly as much of these chemicals. Chlorine requirements drop to a paltry 0.5 ppm, and bromine 1 ppm. Fewer chemicals in the water will make it feel silkier on your skin, and will save you money in the process.
  • It’s safe and environmentally friendly. Ozone generators won’t leave a smell behind or give the water a funny taste. The only by-product of ozone is oxygen, making it very safe for use – both for you and your hot tub equipment.
  • Say goodbye to chloramines. You know that pungent chlorine-smell that some hot tubs have? This actually comes from combined chlorine, otherwise called chloramines (or bromamines in a bromine tub), and they’re an indication of very dirty water. With an ozone generator, you won’t ever have this issue, and bathers won’t have to deal with these physical irritants.
  • Less shocking. When the day-to-day sanitizer is no longer effective against pollutants, shock treatment is used. This is usually done once a week to keep the pollutants from getting out of control. However, with an ozonator, you won’t have to shock as much as it helps break up the molecules, keeping the water cleaner for longer.
  • Gets rid of TDS. Total dissolved solids are a record of everything that is dissolved in the hot tub water. An ozonator will clump the TDS together, so the cartridge filter can remove them easily.

Why NOT Use Ozone In Hot Tubs?

So far so good, right? 

But everything has its drawbacks. Here are some reasons you might want to hold off on installing an ozonator.

  • It can cause corrosion. The high reactivity of ozone makes it a great cleaner, but that also means it can turn the water corrosive. For this reason you should add a thermal cover to protect the tub’s vinyl cover. Also, the materials in your tub, plumbing, and equipment should be corrosion-resistant to save you the headache of replacing broken parts.
  • It needs to be running often. While sanitizers like chlorine and bromine work around the clock, an ozonator only cleans the water when you run it. An average run time for moderately used tubs is about 4 hours per day. If you use your tub more frequently, you may have to run the ozonator up to 8 hours per day to keep the water clean.
  • It only lasts a few years. Some high end models will only last between 3 and 5 years before they need to be replaced. But many ozonators don’t even last that long, giving between 18 and 24 months of use before needing a new bulb or renewal kit.
  • May not be compatible with your tub. The majority of new hot tubs are equipped to handle an ozonator, but older tubs may have compatibility issues, especially where voltage is concerned. Always double check to make sure the ozonator you’re thinking of purchasing will work with your hot tub model.

How Hot Tub Ozonators Work

Ozonators work by adding an extra oxygen particle to the water, which helps get rid of things like oils, perfume, soap, sunblock and even urine.

This extra particle is added by splitting oxygen molecules into two free oxygen atoms through ultraviolet light (UV) or via corona discharge (CD).

Types Of Hot Tub Ozone Generators

There are 2 types of ozone generators you can use with your hot tub. 

1. UV Ozonators

UV ozonators are the older technology, but remain available as they still do a good job cleaning the water. 

The UV ozonator uses ultraviolet light to split oxygen molecules into free oxygen atoms, which then recombine with ambient oxygen to create ozone.

While they do work well, their bulbs gradually put out less UV over time and will require replacement every 2 or 3 years.


  • It’s unaffected by humidity
  • Can produce ozone in any climate
  • Easy for you to clean


  • Less powerful than CD ozonators
  • Lasts only 2 to 3 years
  • Can be expensive if you have a large spa

2. CD Ozonators

The new kid on the block is CD ozonators, which are slightly better than UV models.

A conductor is ionized by electricity which creates a plasma sheet. This sheet is purplish, and resembles a crown, which is what “corona” translates to in Latin.

In general, CD ozonators are highly effective and physically smaller, which makes them the preferred ozonator choice.


  • Ideal for large volumes of water
  • Last longer than UV ozonators
  • Less replacement of parts on the unit over its lifetime


  • Ionization does not work well in humid climates (60%+ humidity)
  • Lifespan is only 3 to 5 years

CD vs UV Ozonators

If you’re looking for the better ozonator of the two, go with corona discharge. The CD model is more effective, efficient, and will last longer than the UV ozonator. 

The only reason you should lean toward a UV ozonator is if you live in a highly humid climate. Anything over 60% humidity, and you’ll have problems with a CD ozonator. If that sounds like your city, invest in the UV model.

How To Install A Hot Tub Ozonator

Like all things, there’s a learning curve to installing an ozonator in your hot tub. 

This can be a bit tricky if you’re not technologically savvy, and you may want to hire a professional to ensure it’s installed correctly.

Here’s how to install it:

  1. Before you even begin, check that your hot tub can accommodate an ozonator. Most new spas are “ozonator ready” and have a clearly labelled injector tube and ozone jet. Consult the owner’s manual to be sure.
  2. Start by turning off the power to the spa, both at the shut off switch and circuit breaker.
  3. Next up is to figure out the voltage required. It will either be 120 or 240 volts. Different ozonators have different voltages, and the same can be said for your hot tub controller. You may need to call tech support and consult schematics to match everything up properly.
  4. Install the ozone check valve on the ozone suction connection (you may need to snip the line for installation). This valve keeps water from back flowing into the ozonator and ruining it. One end of the valve connects to a tube on your ozonator, and the other to a tube running to the spa. Make sure you install the ozonator to move air from the unit to the spa (the valve may show the directional flow for easier setup). The ozonator won’t work if the flow is reversed.
  5. Loop the tubing using a Hartford loop, which further protects water from getting into the ozonator. Raise the tubing as high as you can (above water level) for extra protection and use zip ties to secure it.
  6. Set up the timers on both the ozonator and spa controller. This makes it easy for the ozonator to work without you needing to be there. Three hours is good to start with, but with increased bather load and frequency of use, you may need to make adjustments.
  7. Fire up the power and run the tub.

How To Maintain A Hot Tub Ozonator

Maintaining the ozonator isn’t half as tough as installing it. You should be checking it once a week as part of your regular maintenance schedule.

How to clean and maintain it:

  1. Test it regularly with ozone test strips or a digital meter to ensure its delivering ozone. Make any necessary adjustments to the ozonator and/or runtime if it needs it.
  2. Keep an eye on the injector. If you’re having issues with ozone getting to the water, this could be the culprit. Make sure it’s well connected and flowing properly, so you don’t end up replacing an ozonator that’s actually working fine.
  3. Look over the ozone check valve for leaks. If this valve is compromised, it can destroy your ozonator.

Should You Get One?

Are hot tub ozonators worth it? We think anything that helps keep your water clean is worth considering. 

Using alternatives like minerals and ozone to rid the tub of impurities, you’ll use less chemicals, save money, and have a healthier tub to relax in.

Categories: Hot Tub Care, Hot Tub Chemistry