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How to use
ultraviolet (UV), as part of an alternative pool
sanitizing program? Ultraviolet
(UV) light can be used as an alternative
sanitizing method to very effectively destroy
microorganisms in swimming pool water. Up to
99.9% of the microorganisms can be destroyed, as
the pool water passes through the UV unit. This
dramatic reduction, in the microbial
populations, helps to better maintain proper
sanitary pool water conditions: reducing the
amount of chemical sanitizer needed to maintain
proper, sanitary water quality and keep the
underwater surfaces free of bacterial or algal
growth. A UV Sanitizer must be used in
conjunction with another sanitizing product:
chlorine, ionizers or mineral purifiers. In
addition, oxidation of waste products must be
accomplished with the use of chlorine, ozone,
shock or hydrogen peroxide. Most commonly a UV
Sanitizer is used with chlorine or bromine and
can reduce their usage by a considerable amount.
Typically, an Ultraviolet Sanitizer is plumbed
inline and operates with the filter pump cycle.
Water passing through the cell is efficiently
sanitized, as the UV light passes through the
microorganism's cell membrane. UV Sanitizers
are capable of killing resistant, pathogenic
microorganisms, such as Giardia and
Cryptosporidium. If problems arise, refer to the
Page, as a source of problem-solving
information, broken down into various
categories. Scroll down the page and click on the linked
or images, in the archived answers below, to access additional information, on that topic or product.
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Problem-Solving Information, in a question and
UV And Reducing Chlorine Usage And Odors?
Good morning. We are working on a
municipal pool project where we are recommending a UV
sanitizer to improve indoor air quality. The pool consultant
is questioning the reduction of chlorine as a result of the
UV sanitizer. I was wondering if you had any articles or
studies with a quantitative analysis or comparison of
reduction of chlorine as a result of the sanitizer. I have
seen numbers of 50% -70% reduction but can't seem to find
anything to back this up. Any help in this matter is
Switching to bromine will improve air quality. It is
chloramines that cause the odor and, when bromine is used,
bromamines are formed and they are
(UV) Sterilizers will reduce
chlorine or bromine usage, by a considerable amount. The
microbial population, in the water passing through the cell,
will be close to zero. That means fewer bacterial and algae,
left to grow in the pool. UV Sanitizers won't eliminate
microorganisms growing on the underwater surfaces and that
is why some chlorine or bromine must be used. UV offers the
advantage of killing chlorine resistant pathogens such as
Cryptosporidium and Giardia. Both are heath hazards and
difficult to control without UV. In my opinion, every
commercial or municipal pools showed be UV equipped, because
it kills the worst of them and prevents runaway explosions
of algae and other microorganisms.
Sincerely. Alan Schuster, 3/8/2013
Cryptosporidium and Giardia?
I recently returned home, from a
Central American vacation and found out that I had a
cryptosporidium infection, as a result of swimming pool use.
I found out that cryptosporidium, unlike bacteria and algae,
is hard to kill and is resistant to chlorine. How do I
sanitize my pool? Would a UV unit be a good choice, as we do
travel often? Reducing chemical usage would be a pleasant
bonus. Thank you.
Jo B, 12/2/2011
(UV) sanitizers are one of the most effective ways to
eliminate of 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
and algae 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. 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! How much will
be required will depend upon actual bather demand. More
bather 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. Using a
salt chlorine generator,
as the chlorine source, would provide convenience and help
you avoid the build up of calcium or cyanuric acid. 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. I hope
that this information will be helpful.
Sincerely. Alan Schuster, 12/2/2011
► How Does UV
I am interested in getting away from
all the chlorine and the odors associated with the product.
I know there are several types of alternative pool water
sanitizers available, which can reduce or eliminate chemical
usage. I've read up on some of them, but am not really clear
about Ultraviolet. Is this the same as Ozone? How does it
work? Thanks for the help.
Adam J., 11/2/2012
Sanitizers are not ozone. Some ozone generators utilize
UV to produce ozone, but not as a sanitizing agent. UV rays
destroy the microorganisms ability to survive and function,
after passing through the cell membrane. An ultraviolet
sanitizer unit is plumbed inline and effectively sanitizes
the water, as it passes through the cell. This has the net
effect of reducing the overall microbial populations and
reducing the amount of sanitizer necessary to maintain
optimum water quality and to keep the pool algae-free. UV
will reduce the microbial population, but requires a
traditional sanitizer to help keep it that way and to help
the underwater surfaces free of algae. Chlorine is well
suited, in this role, and lower quantities of chemicals will
be required because of the lower microbial populations. Good
water circulation is important and a
robotic pool cleaner
would be a worthwhile addition, helping to keep the
underwater surfaces in algae-free condition. I hope that I
have been helpful.
Sincerely. Alan Schuster, 11/2/2012
About UV Sanitizers?
I have a salt water aquarium and use a
UV light to control bacteria. I have heard of UV units for
pools. Does it work the same way?
Bill E., Ramsey, NJ, 5/1/2009
Yes and No! In both cases the ultraviolet (UV) light is used
to destroy bacteria and keep the populations down. In an
aquarium, there must be a viable bacterial (beneficial types
- not pathogens) population, in order to decompose and
recycle the wastes from the fish and plants. In a swimming
pool, the best bacteria are dead ones. The UV light is used
to keep the bacterial populations as low as possible, so
that the task of pool water sanitizing is easier. Chlorine
or other sanitizers should be maintained, at the appropriate
levels, in order to provide ongoing sanitation. However, the
presence of an ultraviolet sanitizer
will allow for a reduction of as much as 70%, according to the manufacturer, in
the amount of chlorine or bromine required. The
Sterilizer unit will
make sanitizing easier and involve fewer chemicals and
there's nothing fishy about that. When used in conjunction
with a salt chlorine
generator, it will provide greater convenience and
eliminate the odors, handling, storage and buildup problems,
that are frequently associated with chlorine usage. I hope that I have been
Sincerely. Alan Schuster, 5/13/2009
(UV) Or Ozone?
My wife and I want to use something to
sanitize the pool that will reduce the chemicals needed. We
are considering ozone or UV, as neither adds chemicals to
the water. What are the advantages or disadvantages? Waiting
Pete and Roberta, 6/12/2007
It is true that both systems do not, by themselves, add
chemicals to the pool water. However, both of these
sanitizing methods require that the overall pool water
chemistry - pH, total alkalinity, calcium hardness, etc. -
be maintained for bather comfort and to reduce possible
corrosive effects. Ozone will require that a sanitizer such
as, chlorine, Solar-Powered Salt Chlorine Generator, or ionization, be used as a
sanitizer backup. The ozone
generator will reduce the amount of
chemicals used in this backup role.
sanitizers, for most
consistent results, requires a backup sanitizer. Chlorine
seems to make the most sense, inasmuch as it, also, acts to
fill the needed oxidizer role. The
UV sanitizer will greatly
reduce the amount of chlorine needed to act in this backup
role and will destroy irritating and odorous chloramines.
Both ozone and UV have the advantage of reducing sanitizing
chemical requirements. With proper pool water management,
there should be no disadvantages, as compared to a
traditional pool water sanitizer. I hope that I have helped
in the decision making. Good luck.
Sincerely. Alan Schuster, 6/12/2007
► UV And
If the Sun's UV rays destroys chlorine
and bromine, what happens with a UV sanitizing unit? Where
should my chlorine feeder be placed? Thanks for the
opportunity to ask a question.
Sunlight is UV-A and this wavelength does destroy chlorine
and bromine. All residential
UV sanitizers use UV-C
wavelength, (254 nm) which is
different than Sunlight. Thus,
the need to install all chemical feeding downstream of the
UV sanitizing unit. A small amount of chlorine or bromine
will be destroyed by UV-C. However, it is far less than UV-A
loss and the net result of the reduction of chlorine usage
is still far greater than the 2-5% chlorine loss to UV-C.
Install the chlorine feeder last in line. I hope this
information is helpful.
Sincerely. Alan Schuster, 8/17/2005
Do uv sanitizers save as much chlorine
as they say they do?
Gary B., 3/30/2006
It certainly seems that way. All of the water passing
through the cell has its microorganism population reduced to
nearly zero. All you need is some free chlorine to help keep
it that way and to destroy accumulations of organic wastes.
With the UV Sanitizer killing and controlling algae and
bacteria, about considerably less chlorine is required,
under proper circumstances. In a chlorine pool, odorous and
irritating combined chlorine (chloramines) forms and this
requires adding shock treatment. A UV sanitizer is not a
stand alone sanitizer and is frequently used with chlorine,
to great advantage. As the chlorine used up, chloramines are
formed and then are destroyed by the UV, without additions of chlorine.
The end result is a chlorine pool that looks and smells
better. I hope that this information is helpful.
Sincerely. Alan Schuster, 3/30/2006
Sanitizing And Ozone Together?
Is there any systems in which you can
use an ozonator and UV? So no need for Chlorine or Bromine.
Also what are your feelings on Steel vs. Concrete pools
under the vinyl? Thanks.
John S., 4/27/2008
The easy one first. I would choose concrete: it stronger,
doesn't rust and the walls will not bow or flex. You can add
UV Sanitizing and an
Ozone Generator, but as two separate
units. It will virtually assure you that the return flow
will be devoid of living algae and bacteria. However, the
pool walls and water can still support algae and bacteria.
Keeping a low level of chlorine, about 1 PPM, will prevent
growth in the pool and on the walls. The ozonator will carry
the burden of oxidizing wastes and very little chlorine will
actually be required. The odorous form of chlorine will be
destroyed, as the water returns to the pool. There should be
little or no sensation of chlorine. The fact that you will
be able to maintain this low level of free chlorine, with
only minimal amounts of chemicals, will act as conformation
that proper conditions exist and that everything is
functioning properly. If you add the relatively inexpensive
Circulators, to your
returns, that will eliminate any dead zones that could
promote algal and bacterial growth. I hope
that you will find this information helpful.
Sincerely. Alan Schuster, 4/27/2008
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