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Frequently Asked Questions About Ozone in Swimming Pools

  1. What is Ozone?
    Ozone is active oxygen, O3. It occurs naturally in the earth's atmosphere to protect us from the sun's harmful rays. When an O2 molecule gains another oxygen atom, it becomes ozone. It is an extremely unstable state for oxygen, which is why it makes such a powerful sanitizer.

  2. What are some uses of ozone?
    Some common uses are: pool and spa water purification, drinking water purification, waste water purification, and air freshening.

  3. How long has ozone been used to purify water?
    Since the late 1800's.

  4. How long has ozone been used to purify pool and spa water and remove odors from the air?
    Since the mid 1900’s.

  5. How does the ozone used for water purification affect the air we breathe?
    The amount of ozone produced by an ozone generator is insignificant to the normal atmosphere we live in. When dissolved in water, ozone is extremely safe. Excess ozone quickly converts back to oxygen. Note: Do not breathe concentrated ozone gas.

  6. Is ozone the same as "SMOG"?
    No! "Smog" is air pollution created by combustion polluters. While smog contains small amounts of ozone, it is largely composed of harmful chemicals such as carbon monoxide. In fact, smog and other pollutants contribute to the damage of the ozone layer above the earth.

  7. If I use ozone in my pool or spa, will I help replenish the ozone layer?
    No. Because ozone reacts so quickly with contaminants in water and air, it converts back to oxygen within minutes or even seconds. Any ozone molecules that break free from the pool or spa water will convert to oxygen long before they reach the atmosphere.

  8. Will ozone hurt me?
    No! In the quantities necessary to be effective, ozone is very gentle to humans and equipment in the water. However, you should never breathe concentrated ozone gas.

  9. Does ozone have an odor?
    Yes. Depending on the concentration, the odor ranges from slightly sweet to moderately antiseptic.

  10. Will ozone kill bacteria?
    Yes. It is one of the most effective, complete bactericides of all earth's measurable elements. It will kill E. coli, giardia and other lesser bacteria strains.

  11. Will ozone kill viruses?
    Yes. Ozone kills virtually all known forms of viruses in water and air, including the Ebola virus.

  12. How is ozone different from chlorine?
    In the quantities needed for water purification, it has no noticeable odor, taste or color. It is not irritating to humans or equipment. Ozone purifies water and air very quickly and efficiently, 3,000 times faster than chlorine. Ozone leaves no by-products except pure oxygen. In contrast, chlorine leaves a chemical by-product called hypochloric acid and additional salts in water applications.

  13. Will Ozone reduce scum lines and foaming in spas?
    Yes. With proper filtration it can completely eliminate them.

  14. How is ozone produced?
    Ozone can be produced by ultraviolet (UV) light or by corona discharge (CD).

  15. How does ultraviolet light ozone generation work?
    A special lamp gives off a specific wavelength of ultraviolet light which converts oxygen (O2) molecules into ozone (O3) molecules by splitting the oxygen molecules into individual oxygen atoms (O1) which then recombine with oxygen molecules (O2) to form ozone (O3) – get it? This all occurs instantly inside the ozone chamber in the ozone generator, which produces the gas and injects it into the plumbing return line.

  16. How does Corona Discharge Ozone Generation work?
    Ozone is produced by passing air through a high voltage electrical discharge, or corona. A minimum of 5,000 volts of electricity is necessary to create the corona. Air or concentrated oxygen dried to a minimum of -60°C dew-point passes through the corona which causes the O2 bond to split, freeing two O1 atoms which then collide with other O2 molecules to create ozone. The ozone/gas mixture discharged from the CD ozone generator normally contains from 1% to 3% ozone when using dry air, and from 3% to 6% ozone when using high purity oxygen as the feed gas.

  17. Can ozone damage my pool or spa equipment?
    No. In fact, it is very gentle to spas, pools, and equipment. Applied properly, ozone is gentler than any other water purifier in existence. It can however, be an irritant to lesser grades of rubber, such as Buna rubber, sometimes used in cheap pump seals or o-rings.

  18. Can the ozone in my pool irritate skin or eyes like chlorine in pools?
    No! Ozone is very gentle to skin and eyes.

  19. How long will ozone last in my pool or spa water?
    Scientific tests show that Ozone has a half-life of about 22 minutes in water. In residential swimming pool applications, ozone reverts back to oxygen in minutes.

  20. Will water temperature affect ozone?
    Wide variations in pool water temperature will affect how well ozone works, with higher temperatures reducing effectiveness. An ozone generator should be designed and sized for maximum water temperatures and bather load.
  21. Will ozone affect my pH?
    Ozone is pH neutral and will not affect the pool pH level.

  22. Do I still have to filter the water as often?
    Yes. Because impurities are constantly being introduced into the water and the ozone is constantly destroying them, the microscopic remains will need to be filtered out of the water.

  23. Do I still need to add chlorine to the pool?
    Maybe. Ozone is powerful, but because it’s a gas, it’s difficult to put it in touch with every molecule of pool water. A chlorine residual of 0.5ppm, and occasional shocking is recommended to supplement most ozone systems. Larger pool ozonators with high output can reduce the chlorine need even further, perhaps operating with only a monthly shocking, especially when combined with a mineral purifier, algaecides, clarifiers or enzymes.

  24. What kind of maintenance is needed for an ozonator?
    You may need to replace the “chip” on CD units after a few years. UV units will need a new bulb after 3-5 years, depending on how often it runs, and if it runs all year around. After 5 years or so, you may need to replace hoses and injector fittings or check valves. Many ozonators have rebuild kits, in addition to individual parts available. Expect some expense every 2-3 seasons.

  25. Why would I install a pool ozonator?
    If you want to reduce your chlorine demand and chlorine usage, reduce shocking and backwashing, and improve overall clarity and water sanitation – you could look at ozone. In the long run, an ozonator won’t save you money – but your pool water will be more sanitary, with less chlorine required.

Related Product Pages:

Del Ozonators

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Alternative Sanitizers for Pools
Install an Ozonator, Save the Ozone Layer
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Ozone & UV pool and spa water treatment

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