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"Ultraviolet (UV) Spa Sanitizers"
Sanitizes with chemicals and reduces chemical usage.
 

The Pool & Spa Informational Website
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Sanitizers Without Chemicals

Scroll down to browse through some archived SPA & HOT TUB questions and answers.  Please access the Spa Problems Page and other links, at the top of every page, for additional information.

UltraViolet (UV) light can be used as an alternative sanitizing method to very effectively destroy microorganisms in spa or hot tub water.  Up to 99.9% of the microorganisms can be destroyed, as the water passes through the UV unit.  This dramatic reduction, in the microbial populations, helps to better maintain proper, sanitary spa water conditions: reducing the amount of chemical sanitizer needed to maintain water quality and to keep the underwater surfaces free of bacteria and slimy deposits.  Typically, an Ultraviolet Sanitizer is plumbed inline and operates with the filter pump cycle.  Water passing through the cell is efficiently sanitized, as the ultraviolet light passes through the microorganism's cell membrane. 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.   For an alphabetized listing of the entire contents of the website, use the Table of Contents link, on top of every page.

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More information about Ultraviolet Sanitizers can be found on the DELTA ULTRAVIOLET CORP. Preview Page in the "Spas & Equipment" Product Information Section.   Links are available to connect  you to their websites. 


► Cryptosporidium?

I recently returned to the US from Central America and found out that I had a cryptosporidium infection.  I had been in our hot tub since our return.  I went online and found out that cryptosporidium is hard to kill and resistant to chlorine.  How do I sanitize my hot tub?  We have been using biguanide.  Would a UV unit be a wise investment, as we do travel often?  Thank you.

Joyce B., Albuquerque, NM, 12/2/2009

UV sanitizers are one of the most effective ways to eliminate potential problems caused by protozoa, such as Cryptosporidium or Giardia.  It is certainly one of the worst offenders, all of which are usually killed by UV.  Bacteria are generally inactivated, by chlorine disinfectant, in properly maintained swimming pools and spas, in less than an hour at a minimal concentration.  Protozoa, especially Cryptosporidium, are highly resistant and can survive for up to 10 days at typical chlorine concentrations in pools or spas.  You can't use UV alone, because it does not oxidize, will not kill microorganisms on the walls and is not persistent.  Most often it is used with chlorine.  It kills virtually everything in the return flow and chlorine eliminates the wastes and provides persistent continuing sanitation.  If reduced chemical usage is the intent, UV sanitizing is the place to start!  UV treatment will reduce the microbial populations in the return flow to near zero, without the use of chemicals.  How much chlorine will be required, will depend upon actual bather usage.  More usage will require more chemicals.  In order to assure that adequate oxidation and sanitation exist at all times, I suggest that you try and maintain a level of chlorine, at about 1/2 the normal level. The UV unit will help decrease microbial populations and reduce the amount of chlorine, necessary to maintain any given PPM level, by a considerable amount.  Over time, charting the amount of chemicals added, the bather usage and the chlorine level will provide the best indication of actual chemical requirements.  For more information on UV sanitizers go to:  www.deltauv.com  I consider biguanide a poor choice to sanitize a spa.  It adds to the foaming and that makes sanitation more difficult, as the foam harbors microorganisms and the sanitizer level is usually too low.  To truly sanitize a spa, all foam has to be periodically eliminated.  I hope that this information will be helpful.

Sincerely.  Alan Schuster, 12/2/2009

 

The Fewer The Better?

I realize that you must have some chemicals present, in order to have sanitary conditions.  I would rather go with a system or product that allows me to use fewer chemicals.  Currently, I am using granular chlorine and would like to switch because I just don't like the omnipresent chlorine odor.  Helpful advice will be appreciated. 

Bob H., Tampa, FL 2/17/2007

When it comes to spas, I agree that less can be better.  Chemicals tend to build up much quicker in a spa than a pool because of the volumes involved.  Less may be better, but it has to be enough to do the job!  There are several options that do not include chlorine.  An ozonator combined with a mineral sanitizer, an ionizer or a bromine feeder will provide effective sanitation and little or no odor.  Alternately, you could use an UltraViolet Sanitizer and a lower level of chlorine, to provide complete sanitation with reduced amounts of chemicals and less odor.  Either way, the amount of chemicals required for sanitizing purposes will be reduced.  The pH, total alkalinity and calcium hardness will have to be maintained to maintain bather comfort and avoid corrosion.  I hope that you'll find the information helpful.

Sincerely.  Alan Schuster, 2/17/2007

 

Oxidizer And Sanitizer Levels?

I AM A POOL AND SPA SERVICE / MAINTENANCE CO.  I AM PUTTING AN 800 GALLON SPA IN AND DECIDED TO PURCHASE A UV UNIT. I WAS THINKING OF USING HYDROGEN PEROXIDE WITH THIS, BUT DON'T KNOW WHAT LEVEL TO KEEP THE HYDROGEN. PEROXIDE AT.  DO YOU KNOW?  IF YOU HAVE ANY IDEAS ON THE UV AND WHAT ELSE I SHOULD USE, PLEASE ADVISE.   EXAMPLE: UV AND NON CHLORINE SHOCK 1 TIME PER WEEK, UV AND 0.5 CHLORINE ALL TIMES.  LET ME KNOW WHAT YOU THINK. THANK YOU.

ERIK, 12/20/2004

Ultraviolet (UV) sanitizing will reduce the microbial populations in the return flow to near zero, without the use of chemicals.  However, it cannot oxidize wastes or totally eliminate the microbial population in the spa water or prevent the growth of biofilm on the underwater surfaces.  You are correct in recognizing that products such as hydrogen peroxide, chlorine or non-chlorine shock must be used.  How much will be required will depend upon actual spa usage.  More usage will require more chemicals.  In order to assure that adequate oxidation and sanitation exist at all times, I suggest that you try and maintain a 0.5-2 PPM level of free chlorine.  The UV will help destroy irritating and odorous chloramines.  Hydrogen peroxide alone may not adequately sanitize the spa proper.  Chlorine will provide the necessary oxidation and sanitizing residual.  The UV unit will help decrease microbial populations and reduce the amount of chlorine necessary to maintain any given PPM level.  Over time, charting the amount of chemicals added, the bather usage and the chlorine level will provide the best indication of actual chemical requirements. I hope that I have been helpful.

Sincerely.  Alan Schuster, 12/20/2004

I was told UV breaks down chlorine and bromine.  What should I use with my UV system for my spa?  The amount it breaks down is small, compared to the amount that it saves by its effective sanitizing.  Thank you.

Erik, 12/23/2004

UV sanitizers have minimal effect on the chlorine and bromine, because of the choice of wavelengths.  In addition, it will only have an effect on the water that is passing through the cell.  It will still be possible to maintain a chlorine level in the spa.  After the unit is shut off, this chlorine residual will be able to provide continuing sanitation.  The UV should make it easier to maintain a free chlorine level because the UV will destroy chloramines (irritating and odorous) and will reduce the microbial populations that would, otherwise, consume chlorine.  I suggest that you use chlorine and chart the readings and the bather load.  This should enable you be better predict chemical usage.  At first signs of a loss of water quality, you could shock the spa with chlorine, non-chlorine shock or hydrogen peroxide.  The maintaining of about 1 ppm of free chlorine will help assure proper sanitation and water quality.  I hope that this information proves helpful.

Sincerely.  Alan Schuster, 12/23/2004

 

UV And Ozone?

Thanks for your help. I just purchased a new hot tub and it is coming with both a Delta UV Sanitizer attached to the 24 hour low-speed pump and an Ozonator. Both of these units will be running 24 hours a day along with the circulation system. .With two separate units running, do I still need to use Bromine or Chlorine in my tub? I know both the UV and Ozone do different things within the hot tub. We are sensitive to chemicals and are trying to use little to no chemicals, if possible.  I purchased a Magnetizer from your website,  that will be attached to the tub with the UV light and Ozone system running 24 hours a day.  If I need to use Chlorine or Bromine, what is the smallest PPM, I can get away with?

Chris G., 12/7/2008

You are wise to ask this question.  UV Sanitizing is great, but it does nothing to what is growing in the spa.  However, it kills nearly everything in the return flow, including some of the worst microorganisms.  Ozone will oxidize and destroy wastes, but might not positively assure sanitizing.  It is not long lasting, but running it 24/7 will help.  Adding some chlorine will provide a persistent sanitizer.  I would try to maintain 0.5-1.5 PPM.  If the equipment is operating properly, it will take very little chlorine to maintain this level and there should be little or no chlorine odor.  A little sodium dichlor is probably all you require.  If all it takes is a small amount of chlorine, it is confirmation, that proper conditions are being maintained.  Enjoy the hot tub and I hope that I have been helpful.

Sincerely.  Alan Schuster, 12/7/2008

 

Natural Spa Rash?

Hi, first may I say that this is the most helpful page I have come across. Thank you so much. Second, I got the spa to relax and the stress of maintaining it .. is making me more tense!  My husband has come down with a rash, that we have linked to spa use. Which bring me to my question.  You did not mention natural spa chemicals on your site. It uses no chemicals and I only have to treat it once every three months, I do have to purge my unit due to bromine use. My question is, do you recommend this, and what are the downsides?  Thank you so much for your time and expertise!

Kelly C, 4/7/2003

Call me a skeptic!  If you don't control infectious bacteria, such as pseudomonas aeruginosa, you can end up with a rash or worse.  The product that you are using may not be a recognized spa water sanitizer.  Check the label.  Does it have the EPA Registration number that a sanitizer must have?  Evidently, this product, can under certain circumstances, work.  However, I would rather use a product that I can measure and test and that works under virtually all properly maintained conditions.  Unless, you want to risk a repeat, I suggest that you consider a more traditional spa water sanitizer.  Bromine, chlorine, mineral sanitizers or ionizers, in conjunction with an ozone generator or a UV (ultraviolet) Sanitizer will afford much greater protection and better assure bather comfort.  I'm glad that you found the website helpful.  Good luck with your decision.

Sincerely.  Alan Schuster, 4/7/2003

 

► Where Does the Chlorine Go?

Good day, Alan,  We are new to the world of spas here in Florida.  We use chlorine as our sanitizing agent. I don't understand why when you enter a spa and the chlorine and pH levels are where should be, and 30 min. later when you get out, the levels are much lower.  Is this normal? As I said, we are new in this arena.  I didn't realize that you had to add chemicals after, or before, each use.  Guess we can learn something new every day.

Joyce & Jim, Florida, 9/15/2009

The typical pool in your neighborhood has about 60 times more water than your spa.  Add to this the fact that the spa is at a much higher temperature and this will produce more bather wastes.  This means that the typical spa gets more demands put on its sanitizing system than the typical pool.  Sanitizer levels can be depleted very quickly and it just makes sense to test the water and add more chlorine before and after each use.  However, if the spa is equipped with an ozonator or UV sanitizing unit, less chlorine will be used.   Ozone and UV units have controllable effects on the sanitation, while chlorine effectiveness rises and falls with its concentration. These alternative means of sanitizing spas are more flexible and provide a higher degree of effectiveness through use of a backup system.  Much of the chlorine or Ozone is used to destroy wastes that cannot be removed by standard spa filters.  Refer to the archives on a variety of spa and hot tub sanitizer topics.  I hope that I cleared up the mystery.

Sincerely.  Alan Schuster, 9/15/2009

 

Baptistery Sanitizing?

My name is Jessica, I work at a Church.  We have a 500 gallon spa (we use as a baptistery), and are trying to find out what the best type of sanitizer to use for it would be, the baptistery is mostly used 3-5 times a week for a few minutes at a time. With the type of finishing that we have chlorine is absolutely prohibited. I don't know much of anything about ultraviolet lights or the Ozone.  If you could help me figure out what would be the best thing to use that would be great. Thank you for your time.

Jessica R., 2/27/2006

UV sanitizing works without chemicals to control microorganisms, but needs to be used with an oxidizer to eliminates wastes and organics.  The combination on a UV Sanitizer and potassium monopersulfate or hydrogen peroxide should work well and impart very little chemical sensation or odor.  Adding a mineral sanitizer will add a sanitizer backup.  Ozone might be suitable, given there is adequate ventilation, within the church facility.  I hope that this information will prove helpful.

Sincerely.  Alan Schuster, 2/28/2006

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Floatation Chamber Sanitizing?

I'm interested to install a custom made floatation chamber, which uses a very high concentration of Epsom Salts (about 280 kgs/500 litres water).  Due to the extremely high concentration of salt, water is 99% sterile, in order to achieve 100% it's required an additional sanitizer. Which can be the best sanitizer system? Ozonator? UV?  Brominator?  Keeping in mind the high salt concentration, could be any damage to the system?  Corrosion or rusting?

Jorge P., 7/9/2005

Ultraviolet (UV) will sanitize the water without chemicals and in an enclosed space that is very important.  Bromine will sanitize the water and oxidize the wastes, but chemical odors might present a problem in the enclosed space.  Ozone gas will accumulate in the air space and will require special precautions.   While UV will sanitize the water effectively, something must be added to oxidize the waste products.  Hydrogen peroxide can be used for this purpose and would not create an obvious chemical presence.  For more information on UV sanitizing go to:  www.deltauv.com  I hope that I have been helpful.  Enjoy the experience!

Sincerely.  Alan Schuster, 7/9/2005

 

Effect On Bromine?

If the Sun's ultraviolet has a negative effect on bromine, what effect do UV sanitizers have on the bromine level?  Is there a difference with chlorine?  I would like to reduce the use of bromine used in my spa, by adding a UV sanitizer.  Please shed some light on this.  Thank you.

Martin H., 7/23/2005

Sunlight is UltraViolet-A (UV-A) and this wavelength does destroy chlorine and bromine.  All residential UltraViolet sanitizers use the UltraViolet-C (UV-C) wavelength, which is different than Sunlight.  To help minimize the effect of the UV on bromine or chlorine, it is necessary to install all chemical feeders downstream of the UV sanitizing unit.  A small amount of chlorine or bromine will be destroyed by UV-C. In the process those irritating and odorous chloramines will be destroyed.  However, the reduction in the bromine or chlorine usage is still far greater than the 2-5% lost due to the UV-C.  Install the chemical feeder last in line.  I hope this information is helpful.

Sincerely.  Alan Schuster, 7/23/2005

 

How Is A UV Sanitizer Used?

We moved into our new home and found out the spa has a UV Sanitizer.  When I tell people around here about it, no one knows anything about them.  Having one of these should mean I can use lower chlorine levels, but how do I know when the water is safe, the tests strips show you how much to keep your levels at for a normal spa, not for one with this UV device.

Eric B., 7/26/2004

Your UV (ultraviolet) Sanitizer does not register on any test strip.  What it does is sanitize the water, as it returns to the spa.  It cannot sanitize the spa surfaces or oxidize wastes and contamination.  To do this you should use chlorine.  With a UV sanitizer in place, you will require less chlorine to maintain proper conditions and consume less chlorine in the process.  In addition, the UV will destroy the irritating and odorous chloramines.  Just test the water for free chlorine, as would be the case if only chlorine was being used.  In addition, the pH, total alkalinity and calcium hardness need to be maintained.  I hope that I have helped explain the use of the UV device.

Sincerely.  Alan Schuster, 7/26/2004

Proper water chemistry will help to better control and avoid sanitation problems and maintain more optimum bathing conditions.  More information about Pool/Spa Water Testing Products can be found in the Test Equipment Store.

 

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