down to browse through some archived SWIMMING POOL
questions and answers. Please click the Pool
Topics Link, on top of every page, to access a complete
listing of Pool Problem subjects, an alphabetized
Website Table of Contents, Pool Equipment Information,
About Alan Biographic Material and a Pool Glossary. Use
the other links to access additional subject
information. More information about some new and unique
products, for pools and spas, can be found by visiting
The Website Store.
You'll never know what you'll find and that's always
fun. Be better prepared and avoid costly problems!
manage a commercial swimming pool? Commercial
Pools cannot always use the same chemicals that
are used in typical residential pools, because
of the regulations of local health departments.
What is permitted will vary from state to state.
High bather usage can require specialized
equipment and sanitizing practices. Make sure
that your pool is in compliance with the latest
anti-entrapment requirements. If problems arise,
refer to the
Pool Problems 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.
Join our E-Letter Mailing List.
You'll receive 1-3 E-Letters a
month, featuring helpful pool
and spa advice, new product
information and sale
announcements. All we
require is your e-mail address
and you can opt out anytime you
will never be shared or sold.
Problem-Solving Information, in a question and
► Commercial Pool
I recently started taking care of a
commercial pool and am having problems getting the chlorine
levels up. It seems that no matter how many times I
clean/replace the filters, add trichlor sticks or shock with
lithium, I can't get the chlorine level any higher than 1 on
my 4-way test strips. Any suggestions. Thanks in Advance.
Rick S., Bolton Valley, VT,
There are basically two possibilities here. The chlorine
requirements could be so high that the chlorine sticks
cannot keep up with the demand. Unless the chlorine feeder
is oversized and full, it may not be able to dissolve the
product at a fast enough rate and that explains the need for
the shock treatment. Trichlor is not the best way to
sanitize a commercial pool. The other possibility is that
the test strips are not reading properly. This can happen,
if the strips are removed with wet fingers or not stored
properly. I suggest that you use something else to verify
the results. In either case, you must use products and
testers that are allowed for use in commercial pools. State
laws vary, on these matters. LaMotte Insta-Test strips are
approved for use in some commercial pools. Has anyone ever
thought about upgrading the sanitizing? A
generator would be an excellent choice, as it is a benefit
to both the operator and the pool users. Another thing to
consider is the use of ultraviolet sanitizing. It won't
replace the chlorine, but will greatly reduce the amount of
chlorine required, dramatically reduce the chloramine odor
and simplify the water chemistry. I hope that this
information will prove helpful.
Sincerely. Alan Schuster, 4/23/2016
The Water Chemistry?
We run a small community pool and
would like to research a better means of adding chemicals.
The pool uses liquid chlorine and acid and these are added
with feeding pumps, tied into the operation of the filter
and pump. The problem is that the bather use is anything but
consistent and sometimes there is too much chlorine and
other times there is not enough. Are there controllers that
can be added? How expensive are they? Thanks for the help.
B. M., Knoxville, TN, 6/23/2014
Yes, controllers can be added that will help regulate the
addition of the chlorine and acid. It should give you more
uniform conditions. So far as the cost of these controllers
is concerned, I will have to pass. There are several
manufacturers of such equipment. I suggest that you consult
with a pool company that deals with non-residential pools.
There are other chemical saving and highly controllable
sanitizing methods, that are suitable for use in
commercial-type pools. Ozonation, for example, would deal
with the introduction of bather wastes and would decrease
the amount of chlorine required to maintain a satisfactory
level. AutoPilot Salt chlorine generators and
UV Sterilizers are other
possibilities. Browse through the pages on these topics for
more information. Sorry, that I couldn't provide all of the
Sincerely. Alan Schuster, 6/24/2014
The Chlorine Odor?
I operate a commercial indoor pool
that gets a lot of use. The odor is a real problem with some
of the users. I know that chloramines are the cause, but I
can't keep on adding shock, as the pool is very high volume.
I have heard the ultraviolet can make a difference. Is there
any truth to that? Thanks for the time spent.
Frank B., 5/18/2013
In indoor high-use commercial pools, odor can be an
unpleasant feature. You will find the environment of the
pool to be vastly improved, within 1-3 days, after
Ultraviolet Sanitizer System. The UV rays not
only sanitize the water, but dramatically reduce or
eliminate the chloramines. When chlorine combines with
nitrogen-ammonia compounds, chloramines are formed and
produce the chlorine smell that is so obnoxious, irritating
and unhealthy. Less chlorine will be required to maintain
the customary levels and the overall water chemistry will be
less subject to fluctuation and buildup problems. I hope
that I have explained some of the benefits.
Sincerely. Alan Schuster, 5/18/2013
A public pool, that I swim at has had
chronic chloramine build up that has resulted in air quality
issues. The pool is approximately 125,000 gallons with a
high bather load and uses liquid chlorine and muriatic acid.
I know there are a lot of factors that go into reducing
chloramines, but my question is specific to a copper/silver
ionizer. This equipment was installed at this pool for the
sole purpose of reducing chloramines, but there has been no
real improvement. According to the owner, it is working, but
you wouldn’t know it. Chloramines are consistently above 1
ppm and the air is heavy with the odor. They also state that
they shock the pool with liquid chlorine to reach
breakpoint. They do not use MPS for shock treatment. My
question is whether or not the ionization system, they have
in place, is actually capable of breaking down chloramines?
My understanding of copper/silver is that they are
sanitizers via ionization, but not strong oxidizers. Can you
tell me if there are merits to this system with respect to
chloramine reduction? Thanks for any insight. You provide a
You seem to have an excellent understanding of the issues.
Ionization alone will not eliminate or reduce the chloramine
concentration. It should reduce the amount of chlorine
required to maintain a proper free chlorine level, but will
have no effect on chloramines. To destroy or reduce the
chloramine content, oxidation is required. It can be in the
form of chlorine or potassium monopersulfate.
Ozone Generators will reduce chloramines and
odors very effectively, but will still need some chlorine to
act as a backup sanitizer. A salt chlorine generator would
have been a better choice, as it manufactures chlorine,
right in the pool. The water would be stripped of
chloramines, as water passes through the salt cell. State
law might enter into which equipment is best suited for a
public or commercial pool and this should be considered. I
think a better choice could have been made. I hope that this
information will prove helpful.
Sincerely. Alan Schuster, 1/26/2008
With Biguanide In A Spa?
I manage a large commercial spa. It is
indoors, contains 1800 gallons and is heated to 103'. The
bather load is about 80 people per day. The filter runs
about 10 hours a day on high speed. Currently I am using a
Biguanide system. I am very unhappy due to the complexities
involved and because I am having problems maintaining water
clarity. Chlorine is not an option because of the odor and
irritation. From the information I gleaned from your
web-site, I am considering converting to Bromine with UV
sanitizer and ozonator. As far as the bromine is concerned,
do I go with the tablets or 2-part system? What do I use for
shock? How do I size the proper ozonator and UV? Thanks for
a great web-site. Sincerely.
A. H., New York, 10/5/2008
I am shocked that the NY health department allowed you to
maintain a commercial spa , in that manner. Whoever talked
you into biguanide was only concerned about their profit
margin. You need to treat this, as if it were a pool, as
that is what the bather load demands. The
Ultra-Violet Sanitizer and bromine feeder, should be sized
to treat a pool. Your three fold approach is sound and is
what I would recommend. I would use an inline bromine
feeder and try to keep the level at 3-5 PPM. The ozonator
will make it easier to do and allow you to use less bromine,
to maintain any given level. The UV
Sanitizer makes perfect sense, as it kills virtually all
microorganisms, includes the worst offenders. If you add
some sodium bromide to the water, you can use chlorine to
shock the spa, as the chlorine will convert to bromine.
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. However, it cannot oxidize wastes or totally
eliminate the microbial population in pool or spa water or
prevent the growth of biofilm on the underwater surfaces.
Products such ozone or bromine must be used, in conjunction
with UV. How much 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 bromine, at about the normal level or 3-5
PPM. The UV unit will help decrease microbial populations
and reduce the amount of bromine, necessary to maintain any
given PPM level, by up to 70%. Over time, charting the
amount of chemicals added, the bather usage and the bromine
level will provide the best indication of actual chemical
requirements. I hope that this information will be
Sincerely. Alan Schuster, 10/6/2008
► Clouded Up?
I am on the board of a homeowners pool
and a recent grad of a CPO course however, I need some help
on a problem. Our pool is 80,000 gallons. The pH reading is
7.2, FAC is 2 ppm, TA is 220. We use Calcium Hypochlorite as
our sanitizer. Our pool opened today and the water was
crystal clear. The ambient temperature was 91 °F. Not sure
of water temperature. Four hours into our first day the
water started to become cloudy. Two hours later very cloudy.
We backwashed the filters. Additionally, according to my CPO
book we should try the acid column to convert the C03 to
C02. I have read several of your answers regarding TA. I am
more concerned with the cloudiness. Any help?
It would have been nice to know what the calcium hardness
reading was? The use of calcium hypochlorite will raise the
calcium level, the pH and the TA. Your TA is already too
high and it is likely that the calcium reading is in the
hundreds of PPM. That can account for the cloudy pool water
problem. Depending on the makeup of the dissolved mineral,
lowering the TA might prove difficult, but it should be
tried. I suggest that you consider using something other
than calcium hypochlorite. Liquid chlorine would seem
logical. Even better would be a
salt chlorine generator.
Otherwise, the increasing calcium hardness levels will only
cause more and more pool water clarity problems. Adding
mineral treatments will help to an extent, but is not a long
term solution. I hope that I have been of assistance. Good
Sincerely. Alan Schuster, 5/19/2010
Having a bit of a bizarre issue with
the pool which I run! The Alkalinity is always a bit low
(65-75ppm) so have been adding sodium bicarbonate to the
pool to bring it up a bit, I use sodium hypochlorite as the
disinfectant. The levels of disinfectant are measured in
redox only (this is the only one I've ever come across that
does not have the PPM reading on as well) which only
measures the disinfectant activity and not quantity. Every
time, I add sodium bicarbonate the chlorine goes up. does
adding bicarbonate interfere with the redox reading, thus
causing it to dose more chlorine? Or is it just a freaky
coincidence? I really hope you can help as most people run
at the mention of redox controllers. Not sure buying a new
controller is an option? Yours in anticipation.
Julie, United Kingdom, 8/15/2005
It is not a matter of interference. The controller is
measuring the Oxidation-Reduction Potential (ORP). As
expected, adding chlorine causes the reading to rise. The
ORP is based on the hypochlorous acid concentration, which
rises as the PPM of free chlorine increases. This same
reading falls as the pH rises and rises as the pH drops, due
to the equilibrium between the hypochlorous acid and
hypochlorous ion concentrations. In your case, adding sodium
bicarbonate causes the pH to nudge upward, lowering the ORP
and causing the controller to add more chlorine to raise the
ORP. In order to maintain proper pH and chlorine conditions,
the pH and ORP must both be under control. So long as the pH
is within the desired 7.2-7.6 range, the controller will
keep the chlorine at the proper level. I hope that this
information proves helpful.
Sincerely. Alan Schuster, 8/15/2005
and Indoor Salt Chlorinator?
We have two pools/spas with chlorine
generators. I read where a stabilizer is recommended, but
these are indoor (hotel) pools, so why would I need the
cyanuric acid? Thanks for your time!
Steve, Iron River, MI, 3/37/2007
I don't know where you read that. I see no reason that
Cyanuric Acid should be required. UV is an outdoor problem.
Dichlor is used, indoors, because it is quick dissolving and
essentially pH neutral. My guess is that the instructions
were not written with an indoor pool in mind. I hope that
this information is helpful.
Sincerely. Alan Schuster, 3/27/2007
I have a large group coming into our
municipal pool. How can I be sure that the pool will
accommodate that number of people?
M. C., 9/8/2005
According to CPO information, the following calculations are
Commercial Pools: Surface Area in Square Feet divided by 24
= maximum bathers.
Commercial Spas: Surface Area in Square Feet divided by 10 =
Please verify that this information is current or applicable
to for your area.
Sincerely. Alan Schuster, 9/9/2005
Salt Chlorine Generators?
We operate a resort with 5 pools,
ranging from about 50,000 to 300,000 gallons. All are
commercial hotel/resort pools that get a lot of use. Most of
the chlorine generators, I've see have limits of 25,000
gallons. Would it feasible to put more than one on a pool in
series or parallel? Would that work? Or is it not a good
idea on a commercial pool?
Mike R., 2/11/2008
Many salt chlorine generators are
designed and sized for residential
pools. Others are specifically
designed for the
commercial, resort or municipal segment, of the market.
Multiple units can be used to accommodate larger pools. With
a salt chlorine generator, over-sizing is better. It
provides a reserve capacity that helps pools cope
with periods of peak usage. The proper sizing of a salt
chlorine generator, for commercial use, is dependent on the
following factors: pool volume, maximum bather load
throughout the entire day, circulation pump run hours per day,
indoor or outdoor location, inclusion of special water
features, water falls, fountain heads, negative edge, wave
making, slides, etc and what is the maximum water
temperature the pool can reach, at the hottest part of the
summer. My recommendation would be
AutoPilot, for two
reasons. They have a complete line of units, to accommodate
pools of all sizes and situations just like yours. In
addition, they thoroughly know the topic of
salt chlorine generators
and have the expertise that you require. When I have a
question, I ask them. I hope that this will help with the
Sincerely. Alan Schuster, 2/11/2008
This is not your standard question
regarding chloramine reduction. As a Health Inspector I deal
with this issue a lot but here I want to ask about speed.
Specifically the speed at which breakpoint can be achieved.
A health club that closes at 10:00 pm and opens at 5:00 AM
tries to beat the clock in super chlorination. With
chloramines that reach 1-2 ppm, how fast can breakpoint be
achieved with conventional shocking with liquid chlorine?
125,000 gallon lap pool. The CDC discusses contact time in
cases of liquid stool contamination. Double the dose of
chlorine results in half the time needed for contact. Can
this same principle be used in chloramine elimination? 1.0
ppm CC conventionally requires 10 ppm chlorine to reach
breakpoint (actually 7.5 or so but who's counting). What
about 1.0 ppm CC hit with 20 ppm chlorine? Potassium
peroxymonosulfate could be an option, but they do not have a
test kit to deal with the interference on testing chlorine.
Seemingly pointless, if you don't know you have reached
breakpoint. Alan, please hurry! Thanks!
Tim R., 2/16/2008
All chemical reactions, and destroying combined chlorine is
a chemical reaction, are partially governed by
concentration. This is really a physical chemistry problem,
but simply stated, time, temperature and circulation have to
be considered, as well. Raising the concentration, will cut
the reaction time, but even that is effected by variables. A
pool is full is organics, that given time, will form more
combined chlorine. If there is 1 PPM of combined chlorine at
pool closing time, adding 10 PPM of free chlorine might not
be enough, because of the organics present reacting with the
free chlorine or the formation of more combined chlorine,
from the nitrogenous wastes. Adding 10 PPM of free chlorine
could still leave you with more than 1 PPM of combined
chlorine. No two pools or situations are the same, so a set
figure might not always work. If 10-1 does not produce a
combined chlorine of less than 1 PPM, while leaving a free
chlorine level, within your state's guidelines, I can see
the utility of adding 12-1 or 15-1 or more. Potassium
monopersulfate would be an alternative worth looking into.
It might be used, in conjunction, with the regular dosing of
liquid chlorine. LaMotte Company offers
MPS test strips. I
am not sure what your state allows, in terms of alternative
sanitizing, but salt chlorine generators,
or UV Sterilizers can go a long way towards improving
swimming conditions and compliance with the sanitation
requirements. I hope that I have been of some help.
Sincerely. Alan Schuster, 2/16/2008
I operate a 240,000 gallon painted
plaster outdoor pool; after using bromine for about 20 years
we switched to calcium hypochlorite in 2004. We never had
any "staining: problem using bromine, just a minor green
algae problem which we handled with the appropriate
algaecide. The summer of 2004 we experienced tan
/light brown/yellowish "staining" - on the walls and floor
of the pool, starting in the diving well, slowly moving out
into the shallower parts of the pool, gradually increasing
in quantity as the summer went on. The pool company I dealt
with said it was a metal stain and had me use metal
treatment products to take care of. Pool was shut down for
several days, chemicals added - all pertinent directions
followed, pool thoroughly brushed, backwashed sand filters
thoroughly and put pool back into operation, using a metal
treatment product on a maintenance basis. However, the
stains began to return. They can be brushed off if done
early in their appearance - but difficult considering the
size of the pool. When you brush it off water in area turns
milky. When I opened pool in 2005 since metal staining did
not seem to be the culprit we switched gears to algae
"staining." I treated pool with shock and algaecide,
initially and on a maintenance basis. But the stains
appeared same as in 2004. Only thorough brushing kept them
somewhat under control for the summer. My question is this?
How do I determine for sure what is causing the "stain" to
form, and then what to do to prevent or control it. The only
thing we changed was switching from bromine to cal-hypo.
Each spring the pool is emptied, then cleaned with TSP and
an acid wash before refilling and putting into operation. We
stay on top of everything else - free and combined chlorine,
pH, alkalinity, calcium hardness, filter cleaning, etc. We
checked the source water for the pool and nothing changed
there. The pool company I work with is at a loss. Any
ideas? Would appreciate it.
Dick W., 3/8/2006
I am not sure that is the answer, but it does fit the facts.
Bromine is acidic and will tend to keep the pH and TA
towards the lower end, unless adjustments are made. It does
not contribute to the calcium hardness. Minerals and metals
tend to be more soluble at lower pH ranges. Cal hypo has a
high pH and will raise the pH and TA, as product s being
added. This tends to decrease the solubility of minerals and
metals, as the pH and TA rise. Adding more and more calcium
hardness over time only makes for more problems. I suggest
that you monitor the calcium hardness and add regular doses
of scale treatment. When the calcium level exceeds 400 PPM,
scaling becomes more likely, as does metal staining. Calcium
hypo may not be the best product to use, in this pool. I
realize that there are cost considerations, but liquid
chlorine would avoid the increasing hardness levels. Have
you ever considered a salt chlorine generator? It will give
you more control and less handling and storage problems. And
the water will smell and feel better. Good luck and I hope
that I have been helpful.
Sincerely. Alan Schuster, 3/8/2006
► A Big Pool
We will be operation of a large pool,
as shown, in the attached photo. Kindly advise best cleaning
solutions that can save money and do the Job. This pool will
be taking a large quantity of Chlorine to avoid algae. Many
thanks for you. Kind Regards.
Rami O. 1/13/2008
Robotic pool cleaners are very easy to use, effective and do
not require any plumbing or installation. They don't just
throw the dirt up for the filter to catch - it actually
removes even the finest sediment and debris. They act as a
moving main drain and as a second micro-filter. It can clean
the pool floor, walls and even the steps. There is not much
that you need to do, other than a simple, occasional
cleaning. There are Robotic Pool Cleaners, that are
designed for larger commercial pools and have the longer
cords and bigger sweeping areas. I hope that this
information help get a cleaner pool.
Sincerely. Alan Schuster, 1/14/2008
operate a 100,000 gallon commercial pool and recently had a
crack develop in a wall. It was repaired and painted over.
It now seems to have reopened and is probably responsible
for a significant water loss. Do you have any suggestions
for making a better repair? Thanks for any help you can
Martin M., Georgia, 4/21/2009
Most likely this is a stress crack and needs to be
stabilized. Products, such as epoxy, can be used, but don't
always work while the crack is under pressure to expand.
The Torque-Lock system is
designed to make structural concrete crack repair, that are
rock solid. If you want to make the proper repair,
this is what you want to use. Good luck and I hope that this solves the problem.
Sincerely. Alan Schuster, 4/21/2009
Return To Top Of Page