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 (O2) and one individual oxygen atom attaching itself to another oxygen molecule. This is ozone and is expressed as O3. it can also be formed when a large electrical discharge passes through oxygen (eg-lighting). It is a relatively unstable, highly toxic gas which decomposes to re0form oxygen and is a very effective bactericide.

Ozone Generators

Ozone generators produce the gas by one of two method; 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 lighting storm is created in the chamber which electronically 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.

Is Ozone treatment new?

No. Ozone treatment has been used for many years, particularly in Europe, for the treatment of municipal water supplies and also large commercial and Olympic pools. Recent ozone technology developments have enabled manufacturers to produce smaller more economical generators, much more suitable for domestic pool and spas.


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 wate, 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 chlroine, always follow the manufacturer's recommendations on maintaining PH.