Ozone pool system and Ionized pools comparison

It’s all about the residual sanitiser. That’s what you’re swimming in!

Over the past few years, secondary sanitisers have become very popular in an attempt to reduce chlorine and other chemical levels in swimming pools. The most common are ozone pool systems and UV (Ultra Violet) systems which work in a very similar fashion. In most instances, these sanitisers leave no residual in the swimming pool, meaning you still need to have a chlorine residual constantly in the pool along with all the associated chemicals.

Ozone pool systems – the facts.

Ozone is produced for swimming pool water by two methods. The UV method where air is passed over a UV bulb, and the radiation creates nascent oxygen and then ozone, or the corona discharge method, a pool Ozonator creates a small lightning storm in an air-filled chamber.

Ozone is an effective and powerful oxidiser that has a very short life. The ozonator produces ozone gas that is injected into the pool circulation system to aid the residual sanitiser. Ozone is becoming a popular backup for chlorine systems and saltwater chlorinators.

The addition of ozone treatment in chlorinated pools has been shown to reduce harmful chloramines and reduce chlorine consumption. This is certainly a benefit when used in public pools where high bather loads create increased chlorine demand which can result in high chloramine levels if the chlorine level struggles to maintain a recommended level, commonly around 2 ppm – 4 ppm chlorine residual. When you detect the smell of chlorine in an indoor public pool, it is a sign that there is not enough chlorine in the water. The smell is chloramines, not chlorine. Chloramines are less of an issue in residential pools.

The claim that there can be a safe reduction in chlorine residual levels and still safely sanitise the water needs some scientific backup given that the water only gets treated one to two times a day with ozone as it passes through the Ozonator, which is a point of a contact sanitiser only, meaning it offers no residual protection for bathers if bacteria or parasites are in the main body of pool water.


  • Ozone is a very powerful oxidiser.
  • Eliminates pool odours common to traditional pools
  • Removes Bacteria, viruses and Hydrogen sulphides.
  • Can assist in reducing chlorine levels in the pool.


  • Ozone Pool Systems are expensive to purchase and maintain.
  • Provides point of contact treatment only and has no residual protection for the bather.
  • Ozone gas is very toxic; the ozone generator must be installed in a way that it will prevent the ozone gas from getting into the main pool water.
  • Ozone requires an additional residual sanitiser, most commonly chlorine and its associated chemicals.
  • Only works when the pump is running.

Ionised pools – the facts.

The benefits of copper and silver in the treatment of water dates back to ancient times when it was found that water in a copper vessel remained algae free and water in a silver vessel remained pure.

Ionized pool systems have been around since the ’60s and are sometimes sold as chlorine free alternatives. These systems rely on a small electric current being passed between 2 heavy metals, copper & silver rods; these rods erode over time, releasing copper/silver ions into the water. The copper/silver ions in the water are not affected by temperature or sunlight. Copper/silver ions continue to work as a residual bactericide/algaecide even when the pool equipment is switched off.

Ioniser systems do require the addition of an oxidiser such as liquid chlorine or chlorine free oxygen-based products or an incorporated oxidant production system (usually very low salt chlorination) to be used to oxidise suntan oils, perspiration, dust and body fats. The annual chemical running costs on these systems are low to midrange.


  • It kills bacteria such as listeria, algae, e-coli and cryptosporidium.
  • It is not hazardous to the lungs and will not cause breathing problems or asthma attacks.
  • Healthier for young children and older adults to swim in.
  • There are no harmful gases being let off into the air.
  • Easy on the eyes, ionized water will not cause eyes to get red, itchy, puffy or irritated.
  • UV rays and evaporation does not have any effect on it.
  • Water is not corrosive, making it better for pool equipment and pool surrounds.
  • No chlorine residual required in the pool water, meaning no need for Cyanuric Acid in the pool.
  • Water can be recycled to the garden or holding tanks without dilution.
  • Residual copper/silver continues to sanitise even when the pump is not running.


  • Although very rare, uncontrolled copper levels can turn blond hair green.
  • Ionizers don’t neutralize organic materials, such as body oils, natural suntan lotions, pollen, dirt or urine. As a result, the level of total dissolved solids, called TDS, must be tested on a frequent basis.
  • If not controlled correctly, high copper can cause surface staining requiring treatment to remove.
  • Ionization isn’t a solo act. Pool ionizers must be used in conjunction with chemical sanitisers. Even though ionization decreases the amount of chemicals you need to clean a pool, some chemicals for standard water balance are still necessary.
  • Due to most health departments recommended chemical criteria regarding chlorine residuals, it is not a preferred option for commercial installations.

The hybrid NKD-R Freshwater System is made up of a digital control unit that supplies and manages current to the electrode assembly (OXI & ION Cell). Electrolysis passes through the copper and silver anodes, releasing the ions into the water. The silver disinfects the water, controlling bacteria and the copper prevents algae growth. The minerals left in the water form a residual that continues to sanitise the water. It is not affected by UV or heat like traditional sanitisers. Not only does this mean you do not have to add additional chemicals such as stabilisers or clarifiers, but the continuous effects of the minerals mean that you can run the system for half the time of traditional sanitisers.

In addition, oxidisation is used as water passes over the oxidising plates producing small, untraceable amounts of chlorine, ensuring organic matter (dust, dirt, oils and body fats) and other contaminants are eliminated from the water.

The result is safe, crystal clear freshwater that is an absolute joy to swim in.


Ozone Pool Systems are an add-on sanitiser and although an effective oxidizer, they can only treat water while passing through the chamber itself. All pools require a residual sanitiser while swimming and with these systems, that residual is chlorine.

Ionized systems such as the NKD-R, although producing chlorine it is considered a by-product and does not need to remain in the swimming pool. The residual in an ionized pool is copper and silver, which leaves the water feeling completely fresh and doesn’t require additional chemicals such as Cyanuric Acid (Stabilizer).

To further understand how the system is different to other sanitisers, read more about why the NKD-R Freshwater Pool System is different.