How to properly use
chlorine stabilizer (cyanuric acid) in swimming pools? Chlorine
stabilizer or conditioner (cyanuric acid) is
used, in outdoor chlorine-maintained swimming
pools, as a means of helping to protect the
chlorine from being destroyed by the Sun's
ultra-violet rays. This helps the chlorine last
longer and reduces consumption. The level of
cyanuric acid is easily determined by a simple
chemical test. In northern areas, a range of
20-40 PPM is considered ideal. In sunbelt areas,
a level of 40-50 PPM, is recommended for pools
not utilizing a stabilized form of chlorine.
Levels between 80-150 PPM are above the ideal,
but are not considered to be a severe problem,
but do require that higher free chlorine levels be
levels, especially over 150 PPM, are thought to
reduce the effectiveness of the chlorine and may
require the maintenance of significantly higher
chlorine levels. Every time a stabilized
chlorine is added, some cyanuric acid is
contributed to the water. When using a
stabilized chlorine, for routine sanitized, it
is best not to use sodium dichlor as a shock
treatment, as that only speeds the rise in the
cyanuric acid content. Liquid chlorine, lithium
hypochlorite, calcium hypochlorite or potassium
hypochlorite are alternatives. The only means of
lowering the cyanuric acid level is to replace
water. The use of a salt
chlorine generator is a better way to utilize chlorine,
while still benefiting, from the protective effects of
cyanuric acid. 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.
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Problem-Solving Information, in a question and
Why Is The Cyanuric Acid Still Too High?
I had a dealer
run a series of tests and the cyanuric acid tested out at
150 PPM Too high. I learned, from your website,
that the level became too high, because of my long term use
of 3" trichlor tablets. I knew that I would have to
replace 1/2 of the water and did not want to have to keep
doing this, because of the trichlor tablets. So. I
decided to go with a
salt chlorine generator, that I saw, on your site.
Now, I have a salt water pool and there should be no more
problems, with cyanuric acid buildups. I had the
cyanuric retested and expected to see a reading of about 75
PPM. Instead, I was told it was 105 PPM. That
doesn't make sense, unless one of the tests was wrong.
Do you have an explanation? Loving the convenience of
the salt chlorine generator. Thank you.
Lakeland, FL, 5/14/2018
Of all the
common tests, cyanuric acid is the least reliable and
reproducible. Most testers only read to 150 PPM,
maximum. So getting
a reading of 150 PPM, does not preclude the probability,
that the true reading was in the neighborhood of 210 PPM.
That would explain why the level only dropped to 105 PPM,
after half the water was replaced. For your pool, 75
PPM is good. Higher levels will mean that you will
have to maintain a higher free chlorine level, in order to
assure proper sanitation. Instead of 1-3 PPM of free
chlorine, you might need 2-4 PPM. It would be in your
long term interest to drop the level closer to 75 PPM, as it
will help the salt cell last longer. LaMotte has come
out with a new
Acid Test Strip, that measures from 0-500 PPM.
This is something that a dealer should have available and
should use to retest all readings over 100 PPM. I hope
that this information is helpful.
Alan Schuster, 5/14/2018
How Much Is Too
What is the acceptable level of
cyanuric acid in a swimming pool? Someone came out to do a
water test and said that my level was 250 PPM, and that I
should drain the pool. They said I should not use tablet
chlorine - only liquid chlorine or my pool would be ruined
in 3-5 years. Is this correct?
P. G., 2/10/2016
Ruined?? No sure about that. A range of
20-40 PPM is considered ideal. In the sunbelt, 40-50 PPM is preferred. There is no question that 250 PPM is
much too high. Such levels can interfere with the
effectiveness of the chlorine and require you to maintain a
higher Free Chlorine level, in order to maintain adequate
sanitation. Not knowing where you are located makes my
answer more difficult. High levels can lead to other water
quality issues in hard water areas. They are telling you not
to use chlorine in tablet form because it will add more
cyanuric acid to the water. Liquid chlorine does not contain
cyanuric acid. I'm not sure about "ruining your pool." I
hesitate to tell anyone - especially if I do not know the
type of pool or construction to drain a pool. If it is a
vinyl pool, completely draining the pool can risk structural
damage or liner shrinkage. If the pool is masonry, it should
be able to be drained. However, I would double check with
the builder. If you don't want to or can't drain the pool
completely, another option would be to pump out some water
every week - perhaps, up to a foot below the skimmer. This
will drop the cyanuric acid level in increments. Once the
level is down, I suggest that you use supplement the
chlorine tablets with a weekly dose of liquid chlorine, as a
means of keeping the cyanuric acid level from rising too
quickly. An alternative to liquid chlorine, that avoids the
buildup problems, is a
salt chlorine generator. I hope that
recommendation works out for you.
Sincerely. Alan Schuster, 2/10/2016
► The Need To
How often should I add chlorine
Bob V., 8/7/2013
Cyanuric acid is usually tested at the start of the season
and is added, if necessary. Most residential pools, using a
stabilized chlorine, will rarely have to add additional;
product, unless large amounts of water have been lost or
displaced. Pools that are maintained on chlorine, but are
not using a stabilized chlorine, may have to replenish the
stabilizer level from time to time, if water is lost due to
backwashing, leaks or overflow. The test is simple and could
help reduce chlorine consumption. To better assure proper
overall pool water chemistry, visit a pool store that has a
very reliable, professional lab such as a
WaterLink SpinTouch Lab,
rather than a less accurate test kit or strip reader. I hope the information
Sincerely. Alan Schuster, 8/7/2013
► Too Much
My pool water was tested and I was
told that the stabilizer level was 200 PPM. I was told that
the only way to lower the level was to replace some of the
water. Is there a chemical that I can add that will lower
the level, without removing water? What happens if I don't
lower the stabilizer level? Thank you.
Austin U., Deptford, NJ, 6/24/2017
Firstly, there is no chemical that you can reliably add to the water
that will remove the stabilizer and lower the level. Such a
chemical was marketed, years ago, but proved to be a
disaster for the pool owner. Secondly, replacing water is
the only effective means of lowering the stabilizer level.
Thirdly, if you don't lower the level you will be forced to
maintain higher levels of chlorine, in order to provide
adequate sanitation. Incidentally, the safest way to lower
the water, without potentially damaging the pool, is to
lower the water to the winterizing level. Do this weekly,
until the level drops below 100 PPM. Testing for Chlorine
Stabilizer will help you keep track of the progress. A level
of 150 PPM is considered too high. At 200 PPM, you are
interfering with the effectiveness of the chlorine. Most
State Department of Health guidelines limit cyanuric acid
levels to below 100 ppm. There is also a move for some
states to limit it to 50 ppm, and for some, 0 ppm (New York
State). The primary purpose behind this is the fear of
Cryptosporidium and E-Coli contamination, affecting
swimmers. Basically, cyanuric acid hinders the speed at
which the chlorine can react and kill germs and viruses. The
lower the Cyanuric acid, the quicker chlorine reacts.
Therefore, the lowering the cyanuric acid level is.
theoretically. increasing the "efficacy" of the chlorine. A
salt chlorine generator is a highly effective way to
maintain a chlorine pool, without contributing unwanted
byproducts, such as excessive levels of cyanuric acid or
increases in the calcium hardness, to the point of scaling
or cloudy water. Most pool testers only test to 100-150 PPM.
A reading of 150 PPM could actually mean the reading could
be 300 or more. A NEW
Cyanuric Acid Strip measures up to 500 PPM, in a
instant. I hope that I have been helpful.
Sincerely. Alan Schuster, 6/24/2017
Stabilizer Content in Tablets?
How much chlorine stabilizer is
present in the chlorine pucks?
Bob B., Marietta, GA, 6/12/2015
About 1/2 the weight of the tablet, ends up as cyanuric
acid, after the tablet has dissolved. The same applies to
dichlor. That is why the cyanuric acid slowly rises, over
time, forcing you to replace water, after 150 PPM is
reached. High levels of CYA make chlorine less effective and
force you to favor the higher end of the 1-3 PPM free
chlorine range. Using a
salt chlorine generator, for your
chlorine needs, completely avoids this problem. Adding an
ozonator or a Solar-Powered Mineralizer will help you use
less chlorine and slow up the rise of the CYA. I hope that
this information will prove helpful.
► Will It Go
I found your website through LaMotte
Company, whose strips I use religiously. I live in Maryland,
have a black plaster pool, around 7 years old, use DE
filter, and stabilized granular and stick chlorine. This
summer we had an unusually hot spell lasting for about 10
days that coincided with an outbreak of green algae, which
I’ve never had before. I seem to be using unusually high
levels of chlorine as well to ward off the algae, but the
chlorine seems to be wearing off more quickly than usual.
I’ve had a couple of water tests done at different stores
with some varying results. However, I did get similar
readings for cyanuric acid (140-150ppm) and
stabilizer-adjusted total alkalinity (55-61ppm). Hardness is
a little on the low end (200-260ppm), pH is 7.2-7.3.
Chlorine readings are as expected low. One test said I had
0.83ppm iron, the other did not detect it. Read your website
about cyanuric acid and have concluded I should try to lower
the 150 reading. I plan to winterize in about a month (with
a professional). My question for you is – does cyanuric acid
dissipate over a period of time? If I don’t replace any of
the water now before winterizing, will it “go away” over the
winter. We usually reopen early April. Your suggestions
would be welcome. Thank you.
Bruce V., Maryland, 9/21/2006
Cyanuric acid will not go away. It can be lowered, only by
replacement of water. You should lower it to under 75 PPM.
High levels will make chlorine less effective, but you will
still get a reading. Your problem could be not enough
chlorine is being added, for the way your pool is being
used. Your hardness is not low and you should not allow it
to rise higher, by using calcium hypochlorite. I would not
recommend dichlor either, as it will cause the cyanuric acid
level to rise. To supplement the trichlor, you should use
liquid chlorine or lithium hypochlorite, as neither will add
to a buildup problem. The iron should be treated by a double
dose of a metal treatment. As long as you are using
chlorine, why not make it easier? A
salt chlorine generator
will do just that and avoid chemical buildup problems. I
hope that this information is helpful.
Sincerely. Alan Schuster, 9/21/2006
Hi, you answered a question for me a
few weeks ago about our cloudy water after opening, and
after giving it time our water looks great. Now I have two
problems. After shocking the pool in the evening, we are
able to maintain a free chlorine reading of about 4 ppm
overnight. I go home at lunch and bring some water back to
work with me to test, and verify that the free and total
chlorine are about 4.1 and 4.5. But, by the time I get home
in the evening the chlorine has dropped to nothing. We have
a chlorinator that we keep tri-chlor tablets in but for some
reason it doesn't seem to be working. We even added some
tablets to our skimmer basket (this is not our normal
practice) just to make sure it wasn't the chlorinator. In
past seasons, if we loaded our chlorinator up, even at a low
setting, it would over chlorinate the pool big time. So we
would always keep about two tablets in and this would last 3
or 4 days, even in hot weather. It's still cool (temp is
about 65) so why are the tablets not working? Is it time to
load the chlorinator up? So every time our chlorine drops to
zero, we shock again, and the same thing happens. Our pH is
now dropping below acceptable range too. The other question
is our stabilizer level. When using the drop turbidity test,
results indicate that level is too high and we have been
able to get it down to 100, with partial water changes.
However, if I test with test strips, they indicate that
there is no stabilizer. It doesn't change color at all. All
other parameters on the test strip are very close to what I
get with a kit, or here at work. If there really was not
stabilizer, this would explain the chlorine not lasting
right? But I thought the drop turbidity test was most
accurate. We have a 24' x 52" above ground pool. Thanks.
Shannon Y., Frankfort, KY, 4/15/2010
The most likely reason that the chlorine levels would drop
like that is if there are algae and bacteria growing on the
underwater surfaces. If that is the case, you might not
notice it, but the walls would be slimy. You need to shock
the pool. Once this material is destroyed, the trichlor
tablets will be better able to keep up. Trichlor is acidic.
You need to add soda ash on a regular, as needed, basis.
Have the pool and tap water tested for phosphates and
nitrates. You may not be able anything about the
nitrates. If present, you positively should do something
about the phosphates. These vital nutrients fuel algae
growth. That would explain the rapid decline in chlorine
levels. Your test strips are not correct. You are using
trichlor and, therefore, zero cyanuric acid is not possible.
You want the level to be under 100 PPM. Otherwise, chlorine
is less efficient. Even then, there would still be a
reading. All test strips are not the same. I suggest that
you try using the
LaMotte Insta-Test product. With all test
strips, take care not to handle with wet fingers and store
in a cool, dark and dry place. I hope that this information
Sincerely. Alan Schuster, 4/15/2010
I am having a problem keep chlorine in
my pool. This problem happened once before and I was told
the cyanuric acid level was high. We drained the pool about
2/3 and started to use unstabilized chlorine tablets in our
feeder. This corrected the problem. The new problem I
encountered was that the unstabilized chlorine tablets turn
to mush in the feeder. I can only put one in at a time or it
clogs the feeder. I started using stabilized chlorine again
and my acid level is back up. Do you have any suggestions on
how to keep chlorine in my pool with out using the
unstabilized chlorine tablets. (a floater is not an option
with my pool type) I have a fiberglass 6000 gallon pool and
live in the Florida Keys where the sun is very intense.
Mary Schick, Florida Keys, 4/5/2005
High levels of cyanuric acid does not prevent you from
maintaining a chlorine level. However, levels over 150 PPM
can make chlorine less effective and can be remedied by
replacing some of the water. The only product that you can
use in an enclosed chlorine feeder are stabilized trichlor
tablets. You can't use an unstabilized product, as it will
disintegrate, release chlorine too quickly and possibly
present an explosive hazard. You are unable to maintain a
proper level because the feeder is not releasing chlorine at
a fast enough rate to satisfy the needs of the pool.
Sometimes, especially during hot weather and periods of
heavy bather demand, you may have to supplement the feeder
with shock treatments. Always try and keep the feeder
relatively full and do not allow all the tablets to
dissolve. As long as you use stabilized chlorine, you will
have to replace water periodically, in order to lower the
CYA level. A much better way to add chlorine would be with a
salt chlorine generator. I hope that this information proves
Sincerely. Alan Schuster, 4/5/2005
► Do I Still
Need Chlorine Stabilizer?
If my chlorine level stays on the high
side would I still need to add stabilizer?
Scott T., 5/6/2005
It all depends on what the cyanuric acid level is. In
northern areas a 20-40 PPM is suggested. In sunbelt areas,
40-50 PPM is frequently suggested. If your chlorine is
staying on the high side, it is because you are adding more
chlorine than is necessary for your pool, under current
conditions. Level above 150 PPM are considered too high and
should be reduced by water replacement. I hope that I have
Sincerely. Alan Schuster, 5/6/2005
Chlorine Stabilizer Does?
I have a new pool surface (aggregate)
that is now 4 weeks old. All the startup chemicals were put
in but I now have a green pool which is really and I mean
really hard to brush off the new surface. I was informed
that I had not stabilizer in the pool as of yet so I bought
that, with a heavy duty bacteria, algae treatment which I
put in last night. I followed all the directions with the
amount and brushing, but this morning the walls still have
quite a bit on them. Is the stabilizer that important, even
to have in with the algae reducer? Thanks.
Bruce C., 4/4/2007
Stabilizer helps make the chlorine last longer and that
makes it important. Unless you get the free chlorine level
elevated, you will not solve the problem. Algaecides and
stabilizer are not enough. I suggest that you add the liquid
chlorine or quick dissolving shock, about a pound/gallon per
5,000 gallons, until the free chlorine level is over 5 PPM.
Don't drag it out! The longer it takes, the more product
will be required. Keep it there until the problem is under
control. You have green water because the sanitizer level
was inadequate and algae took hold. Check the overall
water chemistry as well, as it can be affected by the new
finish. Have the water tested for phosphates and nitrates,
as their presence could promote algae growth and increase
chlorine usage. Make sure that you are testing for FREE
CHLORINE. A product, such as the
provides the right kind of information and is ideal for this
purpose. Easy to use too! I hope this explanation is helpful.
Sincerely. Alan Schuster, 4/5/2007
Chlorine Stabilizer Levels?
I have a very high stabilizer level
and have been told that I must replace 3/4 of the water.
Otherwise the chlorine will be less effective. A friend of
mine, who used to have a pool, said that adding hydrochloric
acid will lower the level without any draining. How come the
dealer didn't suggest that? Thank you for your time.
John P., Kings point, NY 7/25/2009
Very high levels of stabilizer (over 150 PPM) can reduce the
effectiveness of chlorine. The dealer did not suggest that
you add hydrochloric acid (muriatic acid), as a means of
lowering the stabilizer level, because it will not work!
Your friend is mistaken! All it will do is drop the pH and
TA and add to the cost and increase the work to be done. The
only way to lower the stabilizer level is to replace water.
There is no practical chemicals means of lowering cyanuric
acid levels! I hope that I set the record straight.
Sincerely. Alan Schuster, 7/25/2009
High Cyanuric Acid Level?
A question concerning Chlorine and
Cyanuric acid. Many pool maintainers here use large doses of
chlorine to solve any and all problems. They come to us when
they experience difficulties. We have recently measured very
high levels of Cyanuric acid in a number of pools, in excess
of 600ppm. The question is about measurement of chlorine
levels in the presence of a high level of cyanuric acid,
(over 200ppm). As the acid locks the chlorine in, can the
chlorine measurement we take be reliable? We have
photometric and titration systems. Yours sincerely,
Paul C., 2/15/2006
Chlorine doesn't solve everything, as you know. Adding
stabilized shock can make a bad situation worse. It is not
necessarily a case of extreme high levels of CYA interfering
with the test results - the high CYA levels will interfere
with the action of chlorine and make it necessary to
maintain higher than normal levels. As the CYA increases,
chlorine becomes less effective. Unfortunately, the pool
owner does not take this into consideration. At 600 PPM,
there is no doubt that the level needs to be lowered. This
can only be done by a major water replacement. I would guess
that the pool is in the southwest or Florida and that
trichlor has been used for a long time. In addition, dichlor
may have been used a shock. My belief is that if trichlor is
used, dichlor should never be used. Instead, calcium or
lithium hypochlorites, liquid chlorine or potassium
monopersulfate should be used as a shock or to supplement
the trichlor during peak bathing periods. I hope that I have
Sincerely. Alan Schuster, 2/16/2006
► How To
On opening my 26000 gal. in-ground
vinyl lined pool the water tested 130 ppm of cyanuric acid,
390 ppm calcium hardness, scaling/saturation index 0.40,
alkalinity 170. I have an automatic chlorinator, solar
mineralizer, a cartridge filter and heater. What procedures
should I follow to get rid of this problem? What problems
will be caused by this? Our pool store recommended draining
half the pool. But, since we can't afford to buy that much
water we are taking it down a little at a time and adding
fresh water at about four inches down and four inches up.
How many times do we need to do this? How low does the
cyanuric level have to be before we can start using our
chlorinator, mineral purifier and heater? Thank you for your
Susan D., 4/19/2005
High cyanuric acid levels just make the chlorine less
effective and, in turn, requires that higher levels be
maintained. You can use everything right now. Replacing 4
inches at a time, means about a 5% reduction. You'll be
there forever. I suggest doing it about 12 inches below the
skimmer, at a time. In the long run, you will require less
water to get the level down. Try and get the level under 100
PPM. Do not use dichlor, as a shock, as it will only cause
the CYA level to rise quicker. The fact that you are using a
Dual-Ion Purifier/Mineralizer is helpful, as it allows you to
use less chlorine and to maintain a lower free chlorine
level. I hope that I have been helpful.
Sincerely. Alan Schuster. 4/19/2005
And A Salt Chlorinator?
I'm having an inground pool installed
with a salt chlorinator. The dealer recommended that I use
chlorine stabilizer to reduce the workload on the salt
chlorinator. Is this a good idea? Is it effective? Is it a
recommended practice? Could it in anyway interact with the
chlorinator in a wrong way? Thanks in advance.
Marc, Quebec, Canada, 5/11/2006,
Yes!!! Yes!!! Yes!!! No!!!
If you don't add 40-60 PPM, the
salt chlorine generator will
have to produce more chlorine and that will shorten the life
of the cell. Add it! I hope that this information proves
helpful and enjoy the pool.
Sincerely. Alan Schuster, 5/11/2006
► Is There An
I do not like lots of chemicals
"stuck" in my pool and this product stays forever. Is there
an alternative stabilizer for salt water pools?
Most of what dissolves in a pool remains forever or until
you replace the water. Would you rather add it unnecessarily
every month? There is no alternative. If you don't add it,
the chlorine will dissipate quicker and that will result in
having to make the salt chlorine generator produce more
chlorine. That in turn, causes the pH to rise faster and it
will require a new cell on an accelerated basis. Add the
chemical. You only need about 50 PPM. Most pools, using
stabilized chlorine, end up with much higher amounts. I hope
this information is helpful.
Sincerely. Alan Schuster. 4/9/2007
► Out Of
We have a round 27 foot by 52 inch
above ground pool. The pH, Chlorine and total alkalinity are
all in the expectable range. The Calcium hardiness is a
little low (we are treating for that). And the water crystal
clear. Problem is our Cyanuric acid is out of control and
continues to flux between 111 and the current 127 ppm. We
use an in-line chlorinator with one tablet of stabilized
chlorine. We have not added anything other than pH decreaser
and the stabilizer chlorine tables. We have replaced at
least half the water and continue to replace water as
needed. My question is what the heck are we doing wrong?
This Cyanuric acid thing is driving us up the
Don G, 8/22/2010
The level is not out of control and you are not doing
anything wrong. Those stabilized tablets contain cyanuric
acid and, as they dissolve, the level rises. By
supplementing the chlorine with another sanitizer the level
of increase can be slowed down. By adding a
Dual-Ion Purifier/Ionizer, you will be able to get the
same good results with only having to maintain 0.5 - 1.5 PPM of free chlorine.
The chlorine usage will drop, the cyanuric acid rise will
slow and the water will look, feel and smell better. I hope
that this information is helpful.
Sincerely. Alan Schuster, 8/23/2010
I live in the southeast US and have a
new gunite pool. I cannot seem to get my stabilizer level
above 30. I add the recommended amount of stabilizer, and
when I test a week later, it’s still 30 and I have had it
confirmed at a pool supply store. What gives? Thanks.
Rob Wood, 4/26/2007
If you are using a stabilized chlorine, the 30 PPM is
enough. The use of stabilized chlorine will cause it to rise
over time. If you have added stabilizer, on more than one
occasion, to get it to a higher level, there is no simple
explanation for the problem. I am sure there is nothing
wrong with the product. I have been seeing this happen, a
few times a year, for the past 30 years. As far as I am
concerned, it is a testing problem. I have seen it happen
with various brands and testers. This test is evidently
capable of being interfered with by trace minerals in the
water. Something in your water is preventing a true reading.
You have added the product, so just assume that it is
adequate and do not add more, as too much will reduce the
effectiveness of chlorine. I have never seen a satisfactory
explanation for this phenomenon and it evidently is not
important enough to warrant a research effort. I know that
this is not the answer you expected, but I hope that you
will accept this meager explanation and not waste money on
further purchases. Enjoy the pool. It is stabilized.
Sincerely. Alan Schuster, 4/26/2007
And Total Alkalinity?
I have been in the pool/spa business
for about 4 years and have become a little confused about
the relationship between conditioner (cyanuric acid) and
total alkalinity. The more sophisticated chemical testing
software programs we use to analysis water all make a 30%
adjustment for cyanuric acid, in the total alkalinity
readings. But, few if any body every talks about it on the
many informational web sites out there, including yours. Can
you give me a detailed understanding of this relationship,
and if it should really be taken into consideration when
testing for TA?
Stan C., 12/14/2009
Good question!!! The total alkalinity test measures the
presence of all materials, dissolved in the water, that are
more alkaline than a pH of approximately 4.5. In swimming
pool water this includes not only the carbonates and
bicarbonates, but silicates, phosphates and cyanurates as
well. Cyanuric acid is a weak acid and in swimming pool
water forms various cyanurates, which are weakly alkaline.
Typically, other than the carbonates and bicarbonates, only
the cyanurates are present in a high concentration.
Chlorides and sulfates do not have a significant effect upon
the pH or TA. Inasmuch as the TA test picks up all of the
alkaline materials, it does not distinguish between
carbonates/bicarbonates and cyanurates. The purpose, of the
carbonates and bicarbonates, is to create a buffer that will
help stabilize the pH in the 7.2-7.8 range and they are
ideally suited for this purpose. Cyanurates, on the other
hand, will register on the TA test, but are not chemically
well-suited to act as a pH buffer in the 7.2-7.8 range. High
levels of cyanuric acid will inflate the true
carbonate/bicarbonate total alkalinity test readings and,
perhaps, give a false impression of properly buffered water.
To eliminate this error, 30% of the cyanuric acid reading
should be deducted from the total alkalinity reading, in
order to approximate the true carbonate/bicarbonate
alkalinity. The important thing is to consider the ability
of the pool to maintain a stable pH, without the need for
frequent pH adjustment. In hard water situations and in
areas with high TDS, it may be preferable to keep a lower
carbonate/bicarbonate TA because of the possibility of
scaling and cloudy water conditions. I hope that I was able
to explain the theory behind the chemistry.
Sincerely. Alan Schuster, 12/16/2009
► Why Is My
Stabilizer Level Rising?
The level of chlorine stabilizer, in
my pool, has been rising all season, even though I haven't
added any more stabilizer. Why is this happening?
Mike I., Paramus, NJ, 7/2/2004
Every time you add stabilized chlorine, in any form to the
pool, you contribute stabilizer to the water. Slowly, over
time the level rises and rises. You are probably using a
stabilizer chlorine, dichlor or trichlor, for routine
sanitizing. To slow down the rate of increase, I suggest
that you do not use sodium dichlor as a pool shock, inasmuch
as this will only add more to the stabilizer level. There
are other shock products to choose from including: liquid
chlorine, lithium hypochlorite, calcium hypochlorite and
non-chlorine shock. I hope that I've solved the mystery.
Enjoy the summer.
Sincerely. Alan Schuster, 7/2/2004
► Can I Add
I have been using liquid chlorine for
sanitizing and as a shock. I know its a pain to lug home
those containers and I really don't like the acid, but it is
cheaper. If I add chlorine stabilizer will it help? Is it
worth doing? Living in Paradise!
Steve T., Delray Beach, FL, 5/12/2008
Chlorine stabilizer can be used in any outdoor,
chlorine-maintained pool. It will help reduce the chlorine
consumption and help make the chlorine last longer. That
means you will have to lug home fewer containers and have
more time to enjoy Paradise. It will help and it is worth
it. Have a happy!
Sincerely. Alan Schuster, 5/13/2008
Too Much Stabilizer?
First, let me thank you again for the
help you provided last spring. Last year and now this I am
getting high cyanuric acid level readings (approx. 100 ppm).
Last summer I pumped the pool down 12-18 inches and refilled
several times with some minor improvement; looks like the
same routine this year. My question is, would it be a good
idea to use unstabilized chlorine until I get this back to a
normal level? Is there a better way to drop the cyanuric
acid level other than water replacement? Thanks in advance
for your help.
Bill P., 4/7/2005
Water replacement is the only way to lower the stabilizer
level. You can use an unstabilized chlorine and it will
benefit from the stabilizer already present in the water.
You may have to give up some convenience. You might continue
using trichlor or dichlor at a lower level, by using a
non-stabilized shock to supplement the chlorine readings.
You will be using less stabilized product and have a slower
rate of buildup. Or you might consider a
generator. You will give this product some thought, sooner
or later, as standard chlorine treatment is declining. Have
fun and enjoy the season.
Sincerely. Alan Schuster, 4/7/2005
Reason To Lower Cyanuric Acid?
Question: How can I get rid of
Cyanuric Acid? I have a 24 foot round above ground pool. We
recently drained half the pool and added 6,000 gallons of
fresh water. We are currently using a non chlorine chemical
as directed. We have backwashed and vacuumed in addition to
a lot of other procedures we were instructed to do and we
still cannot seem to get clear water. PLEASE HELP! Any
suggestions would be greatly appreciated. Have a beautiful
Wanda P., 6/14/2008
Evidently, you are associating cloudy water with the
presence of cyanuric acid. There seems to be no basis for
this. High cyanuric acid levels can reduce chlorine
efficiency, but is not directly linked to water clarity
issues. Most likely the cloudy water is due to inadequate
sanitizer levels, a filter problem or high calcium hardness.
Having drained 1/2 of the water, the cyanuric acid is
probably a non-issue, even if your pool is being maintained
on chlorine. The only means of lowering the level is to
replace water and this has been done. You should have the
water tested and get back with more specific details,
otherwise, it is difficult to offer assistance on the cloudy
Sincerely. Alan Schuster, 6/14/2008
Adding Stabilizer To The Skimmer?
Hi Alan. Well you are a wealth of
knowledge. Thank you for your website answers. I did not see
the following question and apologize if it is there and I
missed it. We are to add stabilizer to our newly refilled
pool. I need clarification on instructions. When they say
pour directly into skimmer, is that with the basket in
place? The stabilizer does not seem to dissolve much at all
in the bucket of water. How slowly is "slowly add"? We are
to add 4 pounds and the little I put in just seems to sit in
the basket. Thank you.
Becky B., Edgewater, Florida., 3/13/2009
If you would have poured all of the stabilizer into the
skimmer, most likely it would have clogged the lines. It is
slow dissolving and will not dissolve in a bucket of water.
It helps to have a lot of water flowing over the material to
get it to dissolve even slowly. Remove the basket and slowly
pour in no more than 8 ounces. Once it all disappears, wait
a few minutes and repeat, until it is all added. I hope that
I have been helpful.
Sincerely. Alan Schuster, 3/13/2009
Where can I find a liquid chlorine
Bruce P., 4/1/2005
The product does exit, although it is probably not widely
distributed. It would be a relatively more expensive way to
add the chemical. The problem is that cyanuric acid has
limited solubility. Any solution would be fairly dilute and,
considering the quantity usually required, would not be an
efficient or cost-effective way of adding it to your pool.
The best way to add cyanuric acid to the pool is to
broadcast it across the surface. It can take a day or so to
dissolve, depending upon the pH and water temperature. You
may be able sprinkle it into the skimmers, over a period of
an hour or so. Make sure that it is done slowly, so as not
to clog up the system. I hope that I have been helpful.
Sincerely. Alan Schuster, 4/1/2005
My pool supply store told me to add
stabilizer. They suggested I wait for a 48 hour period
without rain to add. Why? Thank you.
Art L., Montville, NJ, 6/10/2004
All I can think of it that you misunderstood their
instructions. I have never heard of that recommendation
before, nor, can I account for any reason for the practice.
Most commonly, the chemical is broadcast across the
surface. It is slowly soluble and can take a day or so to
completely dissolve, depending upon water temperature and
circulation. Weather has no bearing! Enjoy the pool season.
Sincerely. Alan Schuster, 6/11/2004
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