Ozone Swimming Pools & Spas

What is Ozone?


Ozone is a sky-blue gas and is formed naturally by the action of the suns UV (ultraviolet) rays splitting an oxygen molecule (02) and one individual oxygen atom attaching itself to another oxygen molecule. This is ozone and is expressed as 03. It can also be formed when a large electrical discharge passes through oxygen (eg-lightning). It is a relatively unstable, highly toxic gas which decomposes to re-form oxygen and is a very effective bactericide.


Ozone Generators


Ozone generators produce the gas by one of two methods; Ultra Violet Light or Corona Discharge.

  • Ultraviolet light (UV)

Generation of ozone using UV is achieved by passing air over a UV light source and then mixing the gas with water.

  • Corona discharge

In this method, air is passed through an electrically charged chamber. What could be called a miniature lightning storm is created in the chamber which electrically converts the oxygen into ozone.

Note: The concentration of gas produced in both types of systems can vary and care should be taken when selecting a unit to be sure that ozone output is appropriate for your pool or spa.




Ozone is one of the most effective disinfectants and oxidisers available and once introduced into the water it starts to work immediately, killing bacteria and oxidising organic waste. As ozone is not highly soluble in water, the ozone must be injected into the water by either a compressor or venturi system.

However, as ozone is also toxic, all traces must be used or removed prior to reaching the pool. As there can be no residual of ozone, some other form of residual sanitiser like chlorine or bromine must also be used in order to provide continuous protection when the ozone generator is turned off.

Naturally, using ozone as the primary oxidiser, means a much smaller amount of chemicals will be needed to sanitise the pool and provide the necessary residual.


How does it affect other chemical levels?


When using an ozonator in pools and spas treated with chlorine, always follow the manufacturer’s recommendations on maintaining PH.

In pools treated with ozone and bromine, the oxidising power of ozone will regenerate the inactive bromine, reducing the consumption of bromine product.

Ozone remains in the water for only a short time and therefore has no effect on pH or water balance, nor does it contribute to Total Dissolved Solids.

The use of a correctly sized and operated ozone generator with a pool disinfecting chemical (eg. chlorine), will keep a pool clean and reduce the need for shock dosing.


A better alternative


Ancient Greeks found that water kept in silver containers mysteriously purified, and algae didn’t grow in copper water pots. In the late 19th Century, water was passed through various porous materials impregnated with silver, creating positive ions and purifying it.

Today, an ion-generating device can be installed in the circulation system. It is made up of an electrode assembly (a copper and silver electrode) and the electronic control unit that supplies current to the electrodes. Electrolysis then passes either silver or copper ions into the water where the silver disinfects and the copper prevents algae growth. The benefits are numerous:

  • The Ions in the water continue to disinfect even when the system is not running.
  • The Ions are not affected by heat or sun like typical chlorine or salt chlorinators so there is no need to add chemicals such as Stabiliser to protect the water.
  • TDS (total dissolved solids) are at extremely low levels providing crystal clear water.
  • A well-balanced pool using ionisation rather than high levels of chlorine can be backwashed direct to your garden and is better for pool equipment and surrounds.
  • Ions in the water provide a softer feel, making you feel more refreshed and rejuvenated after swimming.
  • Using natural minerals such as copper and silver is a much safer alternative to Ozone gas and typically less expensive in both purchase and ongoing running costs.


There are now many alternatives on the market opposed to standard chlorine or salt chlorinators. They can include the use of Ozone, UV Light, Bioguanide, Hydrogen Peroxide and of course Ionisation. We can only suggest you speak with your pool builder or an experienced consultant as to what is the best solution for your new or existing swimming pool and spa.