Ozone in Pools and Spas


Swimming pool ozone machine generators are designed to produce ozone at adequate levels of ozone to keep your pool bacteria and virus free. In most instances, no additional sanitizer is required. Pools however differ in sizes, type and location. As a result, the ozone demand may be different for different pools and variants of the standard protocol may have to be applied. Ozone is a gas produced from oxygen in an ozone generator. It is widely accepted that ozone is one of the most potent sanitizers. Ozone can be an extremely effective method of maintaining your pool provided certain care is taken.

Protocol for Ozone pool management is as follows:

1. Use of Ozone as the disinfectant.

2. Use of an algaecide if necessary to kill any green or black algae. The key to preventing algae growth is to keep your pool clean and backwash regularly. Algae requires nutrients to grow, these nutrients are typically introduced into the pool in the form of leaves, dust and soil etc.

3. With an Ozone pool, a tablespoon (per 10 000 litres of water) of Aluminum Sulphate should be added to your weir weekly together with an additional tablespoon when dusty conditions prevail to act as a coagulant and bind + settle any basic particles in the water so that they will sink to the bottom and be easily sucked up by the pool cleaner. Aluminum Sulphate also bonds the phosphates that algae feed on and renders them useless. Aluminum Sulphate is known as ALUM, is cheap and sold in most pool shops.

4. To remove any leaf stains etc, a chlorine block can be used, especially on white marbelite pools by gently brushing the chlorine block over the stain. The chlorine block can then be removed and left to dry and used again when needed.

5. PH does not affect Ozone like it does chlorine but for the comfort of the swimmers, the PH of the water should be maintained between 7.0 and 7.6


In order for ozone to be effective in a pool, certain basic cleaning protocols MUST be followed which are summarized here:

  • –  The ozone machine generator must be correctly sized for the pool.
  • –  Keep pool filter clean, backwash weekly to clean filter.
  • –  Keep wire baskets or pump baskets clean, remove any debris daily.
  • –  Pump must run for a minimum of 12 hours daily, timer should be set to runthe pump for 3 hours every 6 hours. i.e. 3 hours on / 3 hours off / 3 hourson…
  • –  Brush pool sides at least weekly.
  • –  Remove any leaves or other debris floating on the surface of the pool daily.

    – Use algaecide as necessary to remove any green or black algae. (The less dirt and debris that enters the pool, the less likely algae is to grow.)


    1. 1)  Venturi is to be installed on the return pipe going back to the pool after the pump master flow controller. Water flow through the Venturi unit can only flow in one direction and this is shown by an arrow on the Venturi.
    2. 2)  The non return valve can only be installed in one direction and direction of flow can be tested by sucking air through the unit.
    3. 3)  Ozone generator power should be connected to the pump so that the Ozone generator only switches on when the pump switches on. This can be done by either wiring the unit directly into the pump connections on top of the pump or by wiring the unit into the pump feed on the distribution box.
    4. 4)  It is important that the earth wire from the Ozone generator is connected to the earth point within the distribution box.
    5. 5)  When the Ozone generator unit is powered, the red neon on the front of the box will light up to show that the generator is working. (This light is sometimes hard to see in direct sunlight but clear at night or when shaded)
    6. 6)  If the red neon light does not come on, then it is highly likely that the internal fuse is blown or that the Ozone generator electronics are faulty. In this case, please contact your supplier to test, repair or replace the unit.
    7. 7)  Bubbles of air at your pump return pipe outlet is normal when using an Ozone generator and indicates that the Venturi is functional and sucking air through the Ozone generator as it should.


    Cloudy water can be caused when an ozone generator is first installed because the ozone oxidizes the organics in the water causing them to form a chain, which then becomes visible to the eye and gives the water the cloudy appearance. Another way water can appear cloudy is with an imbalance in the water. Always check to make sure the pH, alkalinity and calcium hardness are balanced. Customers are concerned when, within a day or two of installing their ozone generator, their pool water becomes cloudy. The common reaction is to “shock” the water which clears the water for one or two days before it turns cloudy, and they need to “shock” it again. Shocking the body of water with large amounts of chlorine will break down the molecular chains formed by ozone, but is not recommended. Water will appear clear temporarily, but a few days later the shock is exhausted and the ozone cycle begins again, resulting in cloudy conditions.

    To avoid this cycle, the chains formed by the ozone must be allowed to grow large enough to be filtered and then the water should clear up and stay clear.