You may not heard of a relatively new kid on the block for swimming pool sanitation: Pool ozone.
A pool ozone generator is an an option for home swimming pool sanitation and is a competitor to both salt water and regularly chlorinated pools.
If you had to choose between an ozone vs salt vs chlorine pool, what would you choose and why?
Let’s take a closer look at a pool ozone generator vs salt chlorinator vs regularly chlorinated swimming pool.
What is ozone?
Ozone is a blue-colored gas known by its chemical formula O₃. It’s made up of three O particles. Oxygen by comparison is made up of two O particles and is also known as O₂. So when you add an O particle to O₂ you get O₃.
Back in the early 2000s we began to hear the word ozone used in the context of describing the deterioration of the ozone layer, the part of the Earth’s atmosphere that protects against the sun’s dangerous UV rays. So in that context, the word ozone was mentioned in a positive sense and that damage to it was bad.
Protocols and laws were put into place to limit the amount of ozone-depleting products being produced from aerosol spray cans and refrigerants containing chlorofluorocarbons (CFCs) and halons, dangerous gases that caused the damage. So we removed these gases from various products and became more aware of the dangers of ozone depletion.
But around the same time we also learned about the dangers of direct exposure to ozone given the proliferation of home ozone machines, ozonators, ozone generators and other devices for air purification. While many such products popped up on the market around this time, we tend not hear about them any more due to the faddish nature of them and the potential dangers of them.
But around 2008, we began to hear about how ozone can be used to sanitize pools as an alternative to other cleaning methods. How is this?
What is pool ozone generation?
A pool ozone generator is a system that uses ozone to sanitize, disinfect and clean pool water inside the pipes to effectively replace chlorine as the predominant sanitizing agent to clean the pool water.
You can’t actually buy ozone due to the dangers involved of handling it and being exposed to it. So a pool ozone generation system was designed to produce ozone internally to sanitize pool water while not exposing humans directly to it.
The problem is that the use of ozone in your pool doesn’t actually replace chlorine. In actuality, when you use a pool ozone generation system you still need to manually add chlorine to the water to keep the water clean, just at a lower level.
Why is this?
How does ozone work in swimming pools?
Ozone produced by a pool ozonator has a very short shelf life and only survives for around 20 seconds after it is created before it turns back into oxygen. So when the ozone is created inside the system, it treats the surrounding water which is then returned to the pool for swimming. But there is no residual ozone floating around the pool waiting to sanitize contaminants that enter the pool from swimming and external sources such as rain, sun, organic matter (leaves, twigs, etc) and the like.
That’s the difference between chlorine and ozone and why an ozone-based generator cannot work on its own without some assistance from manually added chlorine or bromine: Chlorine and bromine survives in the pool water for a period of time and waits to be used as needed whereas ozone can’t survive as long.
So when you jump into the pool and introduce sweat, oil, lotion, dead skin, urine and other contaminants into the water, the free chlorine that is available will treat it. Ozone cannot do this since it only survives long enough to treat the water as it passes through the system and then quickly reverts back to O2. Your pool needs something to act as a residual sanitizer when needed.
By adding some chlorine or bromine to a pool with an ozone system, it helps to supplement the ozone’s ability to inactivate contaminants in the water.
Let’s now look at specific options for ozone generation in your pool.
How does a pool ozone generator work?
A pool ozone generator uses ozone gas to treat water to inactivate contaminants that would normally be handled by chlorine or bromine. An ozone generator breaks down oxygen molecules into individual O particles that then get converted to ozone.
Since ozone is unstable, it attempts to stabilize itself by attaching to other particles in pool water and in the air. When this occurs, it oxidizes and kills bacteria and other contaminants to create clean pool water that is safe for swimming.
But in terms of specifically how an ozone generator works, we need to look at the two main options that you can choose from as the process to create ozone is slightly different.
Types of pool ozone generators
There are two main types of pool ozone generators that you will typically see on the market.
Corona discharge pool ozone generator
A corona discharge ozonator or CD ozone generator produces ozone through a electrical discharge or spark. This spark splits O2 (oxygen) molecules into O molecules which then bind to other O2 molecules to produce O3 (ozone).
Product example: DEL Ozone systems are a range of pool sanitizing systems that utilize corona discharge technology to clean water in both inground and above ground pools. While DEL used to manufacture UV-based systems, they now focus on corona discharge technology.
Benefits of these systems are that the ozone produced may destroy contaminants that are normally resistant to chlorine while also breaking down smelly chloramines which can be a problem in chlorinated pools. These systems tend to keep water clearer while also reducing chemical usage.
Ultraviolet radiation pool ozone generator
Ultraviolet (UV) light is used in many applications to kill bacteria in water reclamation, drinking water, waste water and also pool water. The use of a UV lamp in water applications is seen as an efficient and cost effective way to treat water to make it safe for human consumption.
A ultraviolet radiation pool ozone generator is designed to allow water that is passing through the system to be treated for a wide variety of pool contaminants that would normally be inactivated by chlorine.
Product example: Clear O3/Ultra UV2 system from Paramount which uses a UV lamp to convert oxygen to ozone to inactivate organic compounds that pollutes pool water while also inactivating micro organisms like algae, viruses and bacteria.
Benefits of these systems are that they tend to be cheaper to install than the corona discharge models. Modern UV lamps can also last longer than older models decreasing your maintenance time.
Which option is better for your pool?
Corona discharge models are widely considered to be the superior option to UV-based systems for pool ozone generation. Corona discharge models produce a much higher concentration of ozone than do UV-based models although they are more expensive to install than UV products. Corona discharge ozonators use less energy to produce ozone and also tend to require less maintenance and repairs than their UV counterparts.
Corona discharge models also produce ozone at a lower cost over time than do UV models.
The above-mentioned Clear O3/Ultra UV2 system from Paramount is actually two different systems that can be combined together to offer two UV-based systems in one for pool sanitation.
In that regard, you are now seeing manufacturers creating hybrid systems such as the DEL Ozone Solar Eclipse model which combines a corona discharge system with a germicidal UV system for the best of both worlds.
Ozone vs salt vs chlorine pool
Here is a comparison between pool ozone generation, salt water chlorination and regularly chlorinated pool systems.
| Ozone | Salt | Chlorine | |
| Overview | Water passes through the ozone generator and sanitizes the water before it returns to the pool. The active ozone remains in the piping and doesn’t return to the pool. Ozone doesn’t survive very long in the water, around 20 seconds at most. | Uses a cell to electrify dissolved salt and turn it into liquid chlorine. Chlorinated water returns to the pool and is circulated throughout. | Liquid or powder chlorine is manually added to the pool. Chlorinated water is circulated throughout the pool. |
| Chlorine required | Yes, or you can also use bromine as a supplemental sanitizer but at a lower degree than chlorinated pools, up to 80% lower depending on the ozone system. | Yes. Salt is converted to chlorine which should be maintained between 1 ppm – 3 ppm. | Yes. Chlorine should be maintained between 1 ppm – 3 ppm. |
| Sanitizing ability | Ozone is purported to be up to 50 times more powerful at killing bacteria in water and up to 3000 times faster than traditional pool chemicals like chlorine. Ozone can oxidize contaminants like iron and manganese that chlorine won’t. | Salt chlorinators convert salt to chlorine so the sanitizing agent is the same (chlorine) but the process to create it is different. | Chlorine is effective at killing bacteria and keeping pool water clean but it has to be regularly replaced as it dies from exposure to UV and contaminants from pool usage. |
| Sanitizing process | Requires a supplemental oxidizer. Is a good oxidizer and disinfectant but it requires the use of chlorine or bromine as a supplemental cleaning agent. | Standalone. While you use a salt chlorinator to convert dissolved salt to chlorine, you may need to manually add chlorine at times (pool opening and closing, shocking) to supplement chlorine production. | Standalone. You use chlorine to sanitize the pool and don’t require anything else. |
| Contaminants produced | None. | Contaminants attach themselves to chlorine to produce combined chlorine so byproducts (waste) are produced in a chlorinated pool. | Contaminants attach themselves to chlorine to produce combined chlorine so byproducts (waste) are produced in a chlorinated pool. |
| Water balancing effect | None. Ozone has a neutral pH close to 7.0. | Can be significant. pH and other aspects of water chemistry can be thrown out of range when contaminants are high and chlorine is low, algae grows, etc. | Can be significant. pH and other aspects of water chemistry can be thrown out of range when contaminants are high and chlorine is low, algae grows, etc. |
| Cost | A quality pool ozone generator may cost $1,000 – $3,000 to install. Then you also have to buy chlorine or bromine to supplement the ozone. | A quality salt chlorinator system installed may cost around $2,000 on average depending on your pool size and chosen model. | Pool owners can easily spend $300 – $800 per season on chlorine depending on pool size and local weather. |
| Equipment | An ozone generator or ozonator. | A salt chlorinator system, flow valve and salt cell. | None. |
| Maintenance | Depends on the specific product and model. Some may require yearly maintenance and replacement of various parts. | The salt cell needs to be manually cleaned if no reverse polarity feature exists. Very little maintenance otherwise. | Nothing specific since there is no special equipment to worry about. |
| Health | Direct exposure to ozone is very dangerous so the process of using it in a pool is contained within your pool piping only. You can’t actually buy ozone like you buy chlorine or salt. | Salt water is generally regarded as being softer on the skin, eyes and clothing and doesn’t come with the strong smell normally associated with chemical chlorine. | Some people find chemical chlorine hard on the skin, eyes and clothing and some have reactions to chlorine exposure. |
| Damage | Ozone is corrosive and can damage rubber gaskets and seals and other pool equipment in addition to the dangers to humans through direct exposure which must be avoided. | Salt is corrosive and can damage metal, concrete and other parts of your pool. While vinyl and fiberglass is a great choice for a salt water pool, concrete tends to be avoided due to the potential damage. | Chemical chlorine must be safely stored away from children and pets. Excessively adding concentrated chlorine into a salt water chlorinator can damage the salt cell. |
| Weather | Unaffected by local weather conditions. | Direct sun kills chlorine so stabilizer must be used to protect it. Increased chlorine production is required during sunny weather as a result. | Direct sun kills chlorine so stabilizer must be used to protect it. Increased chlorine production is required during sunny weather as a result. |
| Considerations | You still need to use chlorine or bromine to sanitize the pool as ozone only works in the pipes and doesn’t actually enter the pool water. The system doesn’t produce residual ozone that waits to sanitize the water, unlike chlorine. | A salt chlorinator can supply all the chlorine you need during the pool season but you still need some chemical chlorine typically to open and close the pool and possibly for shocking the water. | Chlorine comes in liquid, powder, concentrated powder (shock) and slow dissolving puck form. Chlorine needs to be added regularly to pool water. |
Summary
The earliest I can find references to ozone pool generation systems dates back to around 2008. Oddly, since then they don’t seem to have achieved widespread coverage certainly not as much as traditional chlorine pools or salt water systems which continue to evolve and become more automated.
The main issue that many potential customers might ask is why would I change from chlorine to ozone if I still have to use chlorine? If you have a chlorine pool, buying an expensive ozone system so you can use less chlorine moving forward might not seem like a reasonable trade off.
Then again as a long time salt water pool owner I occasionally use chlorine in my pool too although that tends to be at two specific times of the year only: Pool opening and pool closing.