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What determines the final levels of ozone in water?


=== Many people are under the impression the flow of oxygen/ozone mixture is what determines the final levels of ozone in water. This assumption is only partly correct. There are many additional aspects which have the same or grater effect at the final result of water ozonation as ozone flow does:

  1. Ozone concentration
  2. Water & ozone mixing (that includes a size of bubbles)
  3. Water purity, temperature, pH , etc.

Water used for therapeutic applications is usually produced:

  1. from high purity water (distilled, RO treated, etc).
  2. in small quantity - less then 1 liter
  3. by "passive" bubbling of ozone (no additional mixers are used)
  4. room temperature or colder

I listed all these aspects with one intention only - to show how many of main factors are pre-determined.

As you can see we can still "play" with the concentration and flow of ozone gas, which will ultimately decide what will be the final result...

Let me outline a few important points:

  1. Virtually all ozone generators produce higher concentrations of ozone gas with low flow. Lower concentrations of ozone gas are produced with high flow rate....
  2. Higher flow rates usually produce larger bubbles and opposite - smaller flow rates usually produce smaller bubbles (if the diffuser is properly designed. / By the way, the diffuser should be ozone resistant....)
  3. Ozone transfer from the bubble to water is happening only on the surface of the bubble where ozone is in a direct contact with water. Ozone trapped inside the bubble does not do anything....it just creates problem with strong ozone off-gas. Small bubbles are preferable because of more favorable "surface : volume" ratio => more ozone in the bubble will be in a direct contact with water.
  4. Ozone of higher concentration will have the ability to produce water with higher levels of dissolved ozone.

So, the trick is to find the flow rate & concentration which will deliver the best over all results. That means:

  1. flow will must be large enough to ozonate water in reasonable time....
  2. .... but must be low enough to
    1. create bubbles as small as possible and
    2. to produce ozone concentrations as high as possible.

Rather tricky task..... which can be solved quite easily if proper tools are used. Ozone dissolved in water is usually measured in "ppm" or/and "mg/l" (chemical tests) or electronically in [mV] of ORP (Oxygen Reduction Potential). I use primarily electronic ORP test because I am colorblind, therefore I can not use tests based on a change of the color.

Just for your information - following are a few samples of different applications requiring different ORP levels:

0-150 ORP No practical use
150-250 ORP Aquaculture
250-350 ORP Cooling Towers
400-475 ORP Swimming pools
450-550 ORP Hot Tubs
600 ORP Water Disinfection
800 ORP Water Sterilization
950 AND UP Water for therapeutic use

985 ORP was the level of ozone in water produced by Hansler setup during the training I went trough with R. Viebahn and Dr. Wasser

Many ozone generators currently on the market do not exceed ozone concentrations 50-60 gamma with even the lowest flow rate (1/32LPM). On top of it, majority of producers will provide their clients with following general recommendation:

For ozonation of water use - flow rate 1/8-1/4LPM with maximum concentration which can be delivered by the ozone generator with this particular flow rate(s) ....... that is most of the time less then 40 gamma. Consequently, maximum ORP levels delivered by these systems are usually less then 800-850 ORP - too low for serious therapeutic application. Yes, water with 800 ORP will be sterile, however there will not be enough "ozone stored in water" to deliver substantial therapeutic results.

On other hand, systems which can deliver high ozone concentrations (up to 90-95 gamma) and can be used with very low flow rates (as low as 1/32) are subject to certain drawbacks which are mainly represented by three factors:

  1. ozonation of water with flow rate as low as 1/32 take longer
  2. low flow rates and high ozone concentrations require special miniature ozone resistant diffusers
  3. container which is used for ozonation of water should be properly sealed during the ozonation process and ozone off-gas must be properly destroyed.

ORP levels achievable by systems utilizing 90 gamma concentrations are in range of 1100-1150 [mV] - far more then what could be achieved with concentrations in 50-60 gamma range.

By the way, I believe that all containers used for ozonation of water should be always sealed and excess ozone destroyed - regardless of ozone concentration used for ozonation of water.

I am slowly reaching the end of this ozone & water story.

For those facing the same ozone & water dilemma, I would like to encourage you to do following:

  1. Take your existing ozone setup and try to determine what is the __lowest__ flow rate your diffusing stone can handle - still producing relatively uniform bubbles.

    In case that your diffusing stone does not produce any decent bubbles (pores of the diffuser are too large and ozone is diffused in one large bubble which was "collected and accumulated" from ozone which stayed "hanging on the surface of the diffuser) with flow rate 1/8 LPM and less then you should look for a different style of ozone resistant diffuser.

  2. Check the ozone output from your ozone generator with the flow rate you will determine from your "bubble test".
  3. You may try to use following very rough table I created for you for ozonation of water (1 liter) in a GLASS container which is less the 3" wide:

Flow [LPM] 1/32 LPM 1/16 LPM 1/8 LPM
Flow [cc.min] 31cc/min 62cc/min 125cc/min
Time 15-20 min 10-15 min 7-10 min

By the way.....cc/min => ml/min

As you see, I did not elaborate on ORP levels produced by different ozone concentrations. The reason is that there are too many variables which will effect the final result.

=== One more thing before I will go - keep water as cold as possible. It will "hold more" ozone and it will get saturated faster.

By the way, if you will hear that water can be saturated to a certain point and then it does not "take & hold" any more regardless of ozone concentration used - it is correct. However, saturation point is far above 1300 ORP and it is far above levels of dissolved ozone achievable by simple bubbling of ozone trough water even with very sophisticated passive diffusers (passive diffusers are diffusers which do not employ any additional means to agitate water).

=== The OzoneLab™ Team

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