Alternative Pool Sanitizing

Ozone (O3) is a form of Oxygen (O2) and is a powerful oxidizing agent that can control microorganisms, destroy organic contamination, byproduct build ups, dead algae and organic debris.   It is not a complete sanitizer in the truest sense, because it does not remain in the water for long periods of time.  In a swimming pool, there must be a backup sanitizer such as, chlorine or bromine, usually at about 1/2 the normal level.  Because the ozonator does  most of the oxidizing, far less chlorine or bromine will be required to maintain any given level.  Ozonators, also known as Ozone Generators, can greatly reduce the quantity of the backup sanitizer that would, otherwise, be required.  This is especially important in larger pools, heavy bather usage situations and commercial pools.  The devices that generate Ozone fall into two categories:  UV or Corona discharge.  Commercial pools, larger residential pools or heavy bather load pools should utilize a corona-discharge unit, as it is capable of producing larger amounts of ozone.  With ozonation, the water chemistry should be maintained in the typical manner.  Clicking on the underlined and highlighted "keywords" or "catch phrases," in the archived answers will give you access to additional information on that topic or product.  Please refer to the Glossary, if there are terms or phrases that require explanation.

UltraPure Ozone Generators

► Ozone, Chlorine & ORP?

I have a system with an ozone generator and a controller for pH and ORP on my swimming pool. I keep my pH at 7.5 and my ORP at 700. The one thing I have always been confused about is how long to run my filter pump.  And what should the Chlorine level be?  I've been told I can use almost no chlorine, if I run my system 24 hours a day. Presently I am maintaining a chlorine level of about 0.4 - 0.6 ppm and run my filter for 10 - 12 hours a day, usually for 12 hours during summer and when the pool is heated.  I'd like to minimize chlorine usage.  As I see it, it's a trade off between chemical usage, electricity for the pump and how much chlorine in the water I'm willing to deal with.  Is my practice an acceptable one, or would you suggest otherwise?  Thank you.

Ken C., 4/23/2005

You're right.  It is a trade off.  I suggest that you continue as you are doing.  It is not a good idea to give up on the chlorine, as its presence acts as confirmation that proper sanitation exists.  With the ozone generator, it will take little chlorine to maintain this lower than normal level.  The big negative, about chlorine, is formation of odorous and irritating chloramines.   In your pool, this is not a problem because the ozone destroys the chloramines.  Chlorine acts as a persistent sanitizer and helps backup the ozone.  You seem to have things well in hand.  All I can suggest is that you operate the filter and ozonator for two sessions per day, by dividing the current running times in half.  That way the pool will be without ozone being produced for fewer hours at a time.   For more information about Ozone and Ozone Generators go to:  www.waterquality.net  I hope that I have been helpful.

Sincerely.  Alan Schuster, 4/24/2005

► Ozone: how does it work?

How do pool Ozonators work?  Will other chemicals and chlorine still be required?  Thanks for the help.  Sincerely.

Jason H., Reading, PA, 7/24/2003

There are two common methods of generating ozone in a pool.  Most units pass air over a UV light source, that converts oxygen into ozone.  Others units use corona discharge (electric sparking similar to lightning) to convert oxygen into ozone.  The corona discharge units can produce higher quantities of ozone.  In a swimming pool, the ozone can destroy organic matter, including algae and bacteria.  The Ozone Generator is usually operated in conjunction with the timer and the filter.  Once the Ozonator is shut off, all production of ozone ceases and the ozone in the water quickly leaves - there is no residual effect.  At this point, the pool is subject to microbial growth, especially on the walls and in the corners.  Because of this limitation of ozone, there must be a backup sanitizer, most often chlorine  or bromine.  However, the Ozonator will reduce the amount of chlorine or bromine required, to a fraction of what it would be, otherwise.  So far as the overall water chemistry is concerned, it must be maintained in consideration of water clarity and quality, bather comfort and corrosiveness.  I hope that I have been of assistance.

Sincerely.  Alan Schuster, 7/24/2003

► High Chlorine Levels?

Alan-we have a new indoor pool and are having trouble keeping the chlorine level down.  The pool is used primarily by one swimmer, and is covered around 23 hours per day. We’ve been using a dichlor shock treatment once a week per instructions.  I’ve shut our chlorinator (which uses 3” tablets) off entirely.  With the chlorinator off for more than one week now, and with a shock per above one day ago, our readings are total chlorine (between 3 and 10), free chlorine (10+), with pH, total alkalinity, and stabilizer at normal levels.  When the cover comes off, there is a definite chlorine odor.  The pool has an ozone generator, and the mineral-type skimmer inserts in each of two skimmers.  I suspect that with no sunshine burn off, and limited bather use, there is limited consumption of chlorine.  Is the solution to not shock and dribble in very little chlorine, or shock using less shock product?  We’re literally itching for an answer!  Thanks!

I can see from your email address why the pool is indoors.  I do have an answer for you, but it may not, entirely, be the one you expect.  Stop adding all chlorine:  either in the form of tablets or shock!  Your pool is equipped with an ozonator, mineral sanitizer, is located indoors, is covered most of the time and not subject to high bather loads.  This means that the ozonator and the mineral sanitizer should be more than capable of meeting all of your pool's sanitizer requirements.  The chlorine levels are building up because there is nothing for them to react with - just as you might have suspected.  The recommendations for chlorination and shocking were probably made based on the pool NOT being equipped with an ozonator and mineral sanitizer.  The only time you will ever need to shock the pool is at the first sign of a loss of water quality or after periods of heavy bather usage.  Under these circumstances use a full strength chlorine or non-chlorine shock. The equipment that you have is what I frequently recommend to pool owners that are sensitive to either chlorine or bromine.  I hope that this will solve the problem.

► Ozone Levels?

I received the ozone tester.  What should the optimum reading be?  I see there are 4 levels - 0.01ppm, 0.025, 0.05 and 0.10.  Thanks.

Peter B., 5/6/2005

Thank you for ordering the Ozone Test kit.  I don't believe that there is a standard for ozone.  Ozone is short lived, with about 1/2 lasting for only 20 minutes.  It reacts almost instantly with organic matter, has limited solubility in water and gasses off.  All this conspires to make ozone testing challenging.  It is best done right at the return jet.  The presence of measurable amounts of ozone, in the return flow, confirms that the ozone generator is working.  All that should be present, are the low levels shown on the test kit.  Higher levels, especially in indoor situation could prove irritating.  Equally important are the facts that the ozonator size (output) should be adequate for the spa water volume, that it be operated for sufficient periods of time and that a backup sanitizer, such as chlorine, bromine or a mineral sanitizer be used.  Now that you have confirmed that ozonation is occurring, you need to maintain the backup sanitizer at about 1/2 of the normal concentration.  Good luck with the spa and thanks for ordering the test kit.

Sincerely.  Alan Schuster, 6/6/2005

► Why Aren't Ozonators More Popular?

Ozonators sound like a good idea.  So why are they not very popular?  Is it good for a lazy pool owner?

John W., 6/24/2005

They may not be as popular as chlorine, but their popularity is increasing in all types of residential and commercial pools.  The use of ozone generators has been widespread in spas for many years.  Ozonators are not complete stand alone pool sanitizers.  A backup system, usually chlorine or bromine must be used.  A salt chlorine generator can be used in conjunction with an ozonator and will provide additional benefits.  Mineral sanitizers and ionizers can also be used in conjunction with ozone and chlorine, to provide backup sanitizing and reduce the chlorine usage.  In addition, all of the important water chemistry parameters must be maintained, as in a chlorine-maintained pool.   Yes, it is convenient.  Yes, it will reduce the overall requirements for sanitizer and will simplify chemical balancing.  Yes, it is good for "lazy" pool owners.  There are other choices that might be worthy of your consideration.  Salt chlorine generators can completely eliminate the need for any chlorine and there is no need for a backup.   Still the water chemistry must be maintained.  But isn't that what pool service companies are for?  I hope that I have been of assistance.

Sincerely.  Alan Schuster, 6/24/2005

► Chlorine And Ozone?

I purchased a pool with an ozone generator this last summer and had the pool company come and start it up for me.  They mentioned that if I had a pool service come out to work on my pool they would tell me something is wrong with my pool as there are air bubbles in my filter pump that are being pushed out to my pool - the ozonator manufacturer states this is absolutely normal.  He was telling me that these bubbles will ruin my filters and I will find myself replacing them much sooner than if I didn't have an ozonator.  He at one point bluntly made the statement that they are fancy pieces of equipment that don't actually work - that bugged me.  He also pointed out that the pressure in the filter casing was below 10lbs.  My pool company told me is should be below 10 at all times, if it gets above ten that I need to clean the filters.  This pool service guy told me that it should be between 15 and 20 lbs at all times to keep the filters from expanding and contracting which, according to him (the pool guy), will ruin my filters.  I have been toying with the idea of putting in a switch that will shut off the air flow from the ozonator to see what kind of performance differences I get by running straight chlorine vs. chlorine with an ozonator.  Your comments? Thanks.

Chris K., TX, 4/1/2005

An ozone generator should be installed before the pump, so that the proper venturi effect will be created.  Doing this sends ozone through the filter and results in a cleaner filter with less debris and oily accumulations.  That's why you see bubbles and why there will be longer filter runs.  The pressure is staying lower, in part, because of the action of the ozone.  Unless your filter manufacturer give you information to the contrary, I don't see a problem.  You don't have to install a switch to shut off the air flow to see what will happen.  I can tell you!  You will positively use more chlorine and that should make the "pool guy" happy.  Ozonators and chlorine work well together.  A case of they said vs. he said.  Simple as that.  I hope that I have shed some light on the subject.

Sincerely.  Alan Schuster, 4/1/2005

► Minimizing Chemicals?

After reading more of your advise to others, I am wondering if we could get away with using NO chlorine by using an ozonator along with a mineral pac or an ionizer.  We are getting a small (3,600 gals.) fiberglass pool which will be covered with a 4" spa cover, and will also be under a patio cover, used by 2 adults.  We plan to keep the pool at 87-90 degrees.  What would you recommend?  Would our filter (sand) have to run longer if we do not use chlorine or a salt chlorinator?  What other additives/tests would we need to use, and would we have to be extra careful to add fresh water, because of the pool being covered all the time?  Is it smarter to just go with a salt chlorinator?  Our pool installer is discouraging us from use the salt chlorinator, and if indeed we can get by with no chlorine, that would be ideal.  However, we want to keep things simple as well as clean, and safe.  I'm obviously in the dark about pool chemistry and appreciate any insight that you can offer.  Thanks.

Patty, Tucson, AZ, 10/20/2004

What you are proposing will work.  Just make sure that the ozonator is properly sized for your pool.  The combination of an ozone generator and a mineral sanitizer will work well, even at higher temperatures, as this combination is popular in spas.  For the sake of bather comfort and water quality, the overall pool water chemistry must be maintained in the typical manner.  This combination should not require filtration practices that are different from typical pools of the same size and configuration.  By add The Circulator, you will dramatically improve circulation and eliminate dead zones.  This makes it possible to send ozone to the four corners of the pool, achieving optimum performance.  Another means of minimizing chemical usage is with ultraviolet sanitizing.  Adding a UV sanitizer will allow you to use as much as 85% less chlorine or bromine, killing virtually all of the microorganisms, as the water flows through the unit.  I would still advise the use of a low level of chlorine, as it confirm that proper conditions exist.  All it should take is a 0.5-1.5 PPM level.  There is be little sensation of chlorine and the amount used, to maintain this level, will be much less.  You may not eliminate chlorine, but you will come close.  I hope that this information will prove to be helpful.  Please tell your friends and dealers about the website.

Sincerely.  Alan Schuster, 10/20/2004

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► Ozone And Bromine In A Pool?

Hi, I have a 32,000 gallon pool and I have an OZONATOR and I use Bromine. I have two questions. First the water seems to have a sweet smell, is this due to the ozone?  I have never noticed it in past years.  If it is from the ozone does it mean the ozone level is too high?  My second question is everyone says an ozonator can save on sanitizer. How do I know what level of Bromine to maintain and what are the signs the Bromine level is too low?  Thank You.

D. D., 6/14/2004

A poet once described ozone as smelling like ocean waves crashing on the rocks.  It is possible that you are detecting some ozone, at times when it might be high.  Without an ozone generator you would need to maintain 3-5 PPM of bromine.  With the ozonator, you should be able to manage with 1-3 PPM and it will require less bromine to maintain.  Even if you maintained the same 3-5 PPM level, it would still take less bromine, because of the ozonator.  Bromine levels can be measured by a simple test.  Any sign of a loss of water quality can signal inadequate ozonation or bromine levels.  Cloudy water or algae are the most obvious signs of the need to improve sanitizing.  I hope that I have been helpful.

Sincerely.  Alan Schuster, 6/14/2004