How to use
algae control products in swimming pools? Algae Control
Products have evolved to more than just the
traditional algaecides. The familiar algaecides
include such active ingredients as: Quaternary
(Quats) Ammonium Compounds, Polymers, Chelated
Copper, Silver Compounds and various
combinations. Phosphate Eliminators based on
Lanthanum can be used to help "starve" algae
into submission. Products based on Sodium
Bromide or Ammonium Sulfate are being used to
help control and eliminate problematic types of
algae, mold and slime. Choosing the right
product is important because effectiveness can
vary based upon the problem and the water
chemistry. The use of
as a replacement for standard return jet
fittings, can dramatically improve circulation,
better distributing sanitizer to all areas of
the pool. 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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understand the chemistry and determine the cause of the
problem. Once understood, you can select the best
treatment option. Understanding the nature of the
problem, should be step one. For information about
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Problem-Solving Information, in a question and
White Spots Remain, After Black Mold Treatment?
We have a 16,000 gallon gunite pool colored with light grey
plaster. It is 3 years old and we are located near San
Antonio, TX. Last winter we got some black mold in
shade areas. We bought a black mold chemical online. It
worked great but left lots of white or bleached out specs
discoloring the service. It is not scale but discoloration.
They are small in size such as 1/4" but sadly there are lots
of them. Any suggestions? Thank you.
Jan L., San Antonio, TX 9/15/2018
It sounds like you
added trichlor granules, which are about 90% chlorine,
acidic and slow to dissolve. Your description suggests
that the surface was etched and that the gray colorant was
destroyed. If this is the case, it is not reversible.
Most likely the mold/algae grew in
that area, because circulation was poor and sanitizing
chemicals were not being delivered, to that area. Dead
zones promote growth of algae or mold. Improving
circulation is an important step, in help prevent a
Pool Circulator replaces standard return jet fittings and
turns the return flow into a spiraling pattern, which
reaches areas throughout the pool. This delivers
sanitizing chemicals and makes algae/mold growth less
likely, by improving chemical distribution. Acid
washing the pool, MIGHT soften the color differences.
I hope that this information will be helpful.
► Algaecide Choice With A Salt
We have a saltwater chlorine generator
and have been delighted with its convenience and low
operating cost, not to mention avoiding the hazards of
chlorinating chemicals. We have gotten conflicting advice on
the proper algaecides. Some say copper compounds are fine,
others maintain that their use will damage the electrolytic
cell by plating out metallic copper on the electrodes. My
long-ago college chemistry courses suggest that plating is a
possibility. What is your take on the matter. Thanks!
George H., 12/18/2014
Good old college chemistry! If your
salt chlorine generator
is self cleaning, scaling and plating are usually not a
problem. Except in very
situations, I would not recommend a copper algaecide. You
should be able to use any algaecide that is suitable for use
in a chlorine pool. I would not use the sodium bromide
algaecides, as they can shorten the life of the salt cell,
by increasing the amount of chlorine that needs to be
produced. A polymer formula product, would be my personal
Sincerely. Alan Schuster, 12/19/2014
► Recurring Mustard Algae?
I think that I have a greenish mustard
algae. It can be vacuumed and brushed quite easily. Shocking
the pool does seem to help. The problem is that it comes
back again and again. My pool is an 18 x 36 foot vinyl
pool. What products are best to use so that I can avoid this
Floyd D., Brunswick, GA, 7/23/2013
Mustard algae can be treated in two effective ways and, in
your vinyl pool, both are good. Chelated Copper Algaecides
are effective in controlling this type of algae. The
chelated types of copper algaecide will require additions
every week or two and this will certainly help, in your
case. Your sanitizer level, chlorine I assume, is probably
not being maintained adequately at all times. Make sure that
you maintain a 1-3 PPM level of Free Chlorine, at all times.
Do this and it is unlikely that you will see the mustard
algae problem returning, with any regularity. If you don't
have an automatic pool cleaner, consider adding a
suction-side cleaner to your skimmer intake. These cleaners
are very effective at cleaning and improving the water
circulation on the bottom and can act as a moving main drain, while
operating. Another effective treatment for mustard algae is
the use of one of those "Yellow" Products, containing sodium
bromide. With a shock treatment, it will generate bromine,
which seems to be especially effective against mustard
algae. When shocking a pool make sure that you add enough
product and it is added frequently enough to boost the Free
Chlorine level to 5-10 PPM. Make sure that the pH is
7.2-7.6. Try to maintain at least 1-3 PPM, through the
overnight period. Keep the filter operating continuously,
until the problem is controlled. Once the problem is
controlled resume normal chlorination and filtration. Poor
circulation creates dead zones that promote algae growth.
Better circulation assures better distribution of the
sanitizing chemicals and makes algae problems less likely.
The Pool Circulator is an easy-to-install device that will
dramatically improve circulation and eliminate any dead
spots. I hope that this information will prove helpful.
Sincerely. Alan Schuster, 7/23/2013
► Copper Algaecide Use?
I have been using a copper algaecide
and our water is extremely clean. However, our stairs
develop a yellow stain (it comes off, but keeps returning
every few days). Could this be a result of the product?
Also, I have researched copper sulfate, and the results
indicate it should not be used in pools at 100%
concentration. However, the Canadian government has okayed
the use of this copper algaecide and deemed the 4%
concentration acceptable. Do you agree? I want to keep using
the product as is greatly reduces the upkeep. Thanks and
great web site!
D.T., Windsor, Ontario, Canada, 8/11/2012
Copper sulfate should not be used in a pool! You are not
using copper sulfate. The product is a chelated copper
algaecide that contains 4% elemental copper. It is in a form
that is safe to use and helps avoid staining and
discoloration. This product and all other swimming pool
sanitizers are subject to government regulations, both in
Canada and the U.S. In order to continue manitai9ning good
water condition, you should maintain a proper level of a
sanitizer such as chlorine or bromine. The use of algaecides
provide an additional layer of algae control.
The Pool Circulator
is a circulation booster insert, that dramatically
eliminates dead zones and makes the water come alive. You'll
get better distribution of sanitizers and that should help
minimize algae and other related problems. A newer, more
automated way to get the benefits of copper and zinc ions is
with a solar-powered pool mineralizer. There is no
installation and the metallic electrodes should last for
years and they can be replaced. I hope that I have
Sincerely. Alan Schuster, 8/12/2012
► Freshly Finished Plaster Pool?
Could a maintenance dose of 1.5 oz a
copper algaecide every other week for algae control could
have caused staining or gray streaks? The plaster was about
2-3 months old, when added. Thanks.
Lenny M., 10/29/2017
The use of copper algaecides should be avoided in gunite
pools, for at least 6 months after the pool was been
plastered. This allows for the surface to completely cure.
Otherwise staining is a possibility. If you want to use an
algaecide, I would suggest a polymer formula, as it is both
non-metallic and non-foaming. I hope that this information
will prove to be useful. If this website was helpful in
providing information, please tell your friends and dealers.
Sincerely. Alan Schuster, 10/30/2017
► Added Too Much Algaecide?
Dear Alan, we dropped a bottle of
algaecide into the deep end of the pool. Our 10,000 gallon
(marcite) pool now has 16 ounces of a copper based algaecide
instead of 2 ounces. We have tried partially draining the
pool and refilling, running the filter 24 hours, and of
course, cleaning the filter. We still have an amazingly
green pool and our neighbor said the pool will stain too,
but he didn't have any answers. Our pool store, well, hasn't
been overly helpful. Do you have any advice? We haven't
found any other questions like this online yet. Can you
The N. Family, 5/25/2010
Just because you added too much doesn't have to mean that
problems will, inevitably, result. Today, virtually all
copper algaecides are based on chelated or complexed forms
of copper: the purpose being to avoid staining and
discoloration. In order to reduce this possibility, because
of the overdosing, you should add 1-2 doses of a quality
mineral treatment, such as phosphate-free
soon as possible. These products are formulated to chelate
(complex) heavy metals, such as iron or copper. Once added
the possibility of adverse effects should diminish. Another
better option is to us a METALTRAP Filter and some garden
hose and a small submersible pump. As the water is
recirculated, the copper will be removed. Stop when the
copper levels drops to a safer 0.3 PPM. Good luck and I hope
that I have been helpful.
Sincerely. Alan Schuster, 5/26/2010
► About Sodium Bromide?
I am looking to find some info on
Sodium Bromide. I am a pool professional and I know it works
for killing algae, yet I don't know what the actual process
is for killing it. I have been told everything from it opens
up the algae to let the chlorine kill it to it enhances the
chlorine and gives it faster and stronger killing ability.
Please let me know. Thank you.
Mike in San Diego, 5/20/2008
You gave me about 5 reasons and all are incorrect. It is
really not that complicated. When you add the sodium
bromide and follow with a shock treatment, the bromide is
converted into hypobromous acid: the active sanitizing form
of bromine. Certain types of algae such as yellow-mustard
algae and bacterial conditions such as water mold or "pink"
algae appear to more vulnerable to bromine than to chlorine.
These problematic conditions, that seemed resistant to shock
treatment, are usually controlled and eliminated by the action of
bromine. It doesn't necessarily work, as well, against all
types of algae and bacterial conditions, but against certain
chlorine-resistant problems it is very effective. While it
will help solve the problem and make the water smell and be
less irritating, it will increase the chlorine usage.
The recommended maximum level of sodium bromide is 6 PPM,
when used in outdoor pools, due to the potential of sodium
bromate formation, at high sodium bromide levels. LaMotte has introduced a
Sodium Bromide Insta Test Strip. I
hope that I have shed some light on the subject.
Sincerely. Alan Schuster, 5/20/2008
► Clear Pool Water, But No Chlorine
I believe my pool dealer had me try 5
lbs of sodium bromide, a week and half ago. After adding 4
more gallons of liquid chlorine, I finally got rid off the
persistent algae problem. The weird thing is it's crystal
clear. No slime on the walls or under the water and no haze.
The test kit shows no chlorine and I am concerned. I have a
3 inch tablet floating and I put 1-2 cups of granular in
daily. Any suggestions on why?
The mystery is over. The addition of the sodium bromide
converted the pool to a bromine pool. All the chlorine is
being converted to bromine. Evidently, the type of algae you
had was not responding to chlorine and this chemical
addition helped to solve the problem. The goods news is that
the water will feel and smell better. The downside is that
it is a bromine pool and it is no longer protected against
the Sun's UV rays, as is stabilized chlorine. Your usage
will continue to be higher, until the bromides dissipate
over the years or the water is replaced. Your water is now
clear and chlorine wasn't working, so this is an
improvement. I suggesting adding chlorine , after the Sun's
goes down. Liquid chlorine would be the most cost effective
and unlikely to cause long term buildup problems. To reduce
the pool's overall chlorine/bromine requirements, I would
Dual-Ion Purifier-Mineralizer. It can be used with chlorine
or bromine and will help provide sanitation, especially when
the chlorine or bromine level bottoms out during the height of
a sunny day. You've changed the way the pool is being
sanitized and can make the best of it and get even more
pleasant swimming conditions, as a result of this change. I
hope this puts your mind at ease. Enjoy the season.
Sincerely. Alan Schuster, 6/14/2007
► Which Pool Algaecide To Choose?
I was in the pool store the other day to pick up some
algaecide. I couldn't believe the number of different types.
The prices went from about $5.00 to over 20 bucks. How do I
know which one is best for my pool? A 24' above the ground
Charles H., Clearwater, FL, 6/12/2008
You're right there are a lot of choices. Here's an
illustration: if you're sick and need an antibiotic, taking
aspirin won't necessarily help. Some algaecides are cost
effective and can be used to treat the everyday varieties of
algae: "quat" and chelated copper algaecides are in this
category. Others algaecides are more costly, but are highly
effective in the treatment of resistant algae problems:
Polymer (polyquat) and Silver Algaecides fall into this
category. Being that your above ground pool is vinyl, I
suggest that you consider a chelated copper algaecide: this
product is very cost-effective and provides excellent
results against blue-green and yellow-mustard types of
algae. If in the future, you encounter a resistant type, a
switch to another product can be made. In most instances,
adding a solar-powered
purifier-mineralizer should preclude the
need to add algaecide. There is no installation involved. I
hope that I have been of assistance.
Sincerely. Alan Schuster, 6/12/2008
► Vinyl Pool Algaecide?
I have a inground pool with a vinyl
liner. I have been told conflicting ideas about algaecides.
Can I use any type of algaecide with a vinyl liner? One
company told me I needed to buy a more expensive algaecide
for pools with a vinyl liner. Is this company just wanting
to charge more for a more expensive product? Is any
algaecide ok to use with a vinyl liner? Thank you.
Every algaecide on the market is used with vinyl pools, so
far as I know. If your water contains iron and other metals,
I would not use copper algaecides. If the water is very
hard, I would not use copper algaecides. Otherwise, a
quality copper algaecide is very cost effective in a vinyl
pool. I would not use algaecides that contain dimethyl
benzyl ammonium chloride or similar sounding names, in any
pool, because they usually lead to foaming problems and are
not always effective. They are inexpensive and that makes
them popular. Sometimes, when functioning as a wetting
agent, they make of algaecidal treatments more effective.
Polymer algaecides are expensive, by comparison, but they
work well, do not foam, can't stain and can be used in all
types of pools. Price limits their popularity. Silver
algaecides are relatively expensive, but effective.
There are some staining issues, but usually not in a vinyl
pool. Instead of adding algaecide, you could add a
ionizer/mineralizer. The best algaecide is one that
works. Your call-your budget! I hope that I have helped you
better understand the choices and differences.
Sincerely. Alan Schuster, 5/3/2007
► Borates And Algae Control?
Hi Alan. Great web site! What is your
opinion on the use of sodium tetraborate for algae control
in an inground pool? I believe the release of boron into the
water prevents algae from growing or so they claim. It also
spikes the pH up quite rapidly, which is why they sell it in
a kit form which includes proper amounts of pH down
Tim C., 4/2/2007
The borate products work by lowering the levels of carbon
dioxide in the pool water. Low levels impedes algae growth.
The pH is just over 9, so that is why pH reducer must be
added. There is little doubt that this product can help in
the control of algae. However, you will still have to
maintain a proper sanitizer level, for ideal pool
conditions. For those times when the chlorine level bottoms
out, this product might provide some leeway. If you could
maintain adequate chlorine levels at all times, you might
not see a significant benefit from this product. Most
chlorine products are added in a intermittent basis or
haphazardly and, under those circumstances, borates add an
additional safety margin. However, newer sanitizing methods
such as salt chlorine generators maintain excellent control
of algae by providing a steady, adequate and almost
effortless application of chlorine to the pool. If you are
looking towards improving algae control and water quality, I
would look in this direction. I hope that this information
Sincerely. Alan Schuster, 4/2/2007
► Copper Algaecide?
I used to treat my pool every year in
the beginning with this copper 7% product that took all the
algae's away (blue, black, green, red, yellow, etc.) It was
liquid and it took about two to three cap fulls to clear the
water in a matter of hours. Have you heard of this stuff or
do you know something similar to it I could purchase
Bill M., 4/6/2008
What you are describing is a 7% copper algaecide, although
the concentrations may vary. It is probably a private-label
product. The formula is usually based on a copper
triethanolamine complex, in order to avoiding staining and
discoloration problems. I don't know about capfuls: the dose
is typically a few ounces per 10,000 gallons. It is a
product of choice for yellow-mustard or blue-green algae. It
is used less often for other types. While it is popular in
vinyl pools, its use in gunite pools is limited and should
be avoided, if the pool is less than 6 months old. Most
major product lines include a product of this type. So while
you may not locate the specific brand, you should be able to
find a replacement. By itself, it can help kill and prevent
algae. To solve a problem, it has to be used with shock
treatment. A very convenient way to add copper is with a
dual-ion, purifier-mineralizer. No installation is required. I
hope that I have been helpful. I hope that I have been
Sincerely. Alan Schuster, 4/6/2008
► Should I Add Algaecide?
I had a vinyl inground pool installed
last fall and it was opened this spring for the first time.
The water is under control and clear. Is there a need to add
algaecide as a preventative measure or should it only be
added when necessary/required? Thanks.
Michael, Montreal, Canada, 5/10/2017
The best time to actually add an algaecide is before you
need it. That way, perhaps, you won't need it. It is
arguable that if you maintain proper control of the water
chemistry, an algaecide is not necessary. I would never go
out of my way to add a quat algaecide: dimethyl benzyl
ammonium chloride, as it can cause foaming and interfere
with DE filters. A polymer algaecide is always a good
choice, but it is expensive. Copper algaecides are cost
effective and are, generally, a good choice for a vinyl
pool. In short, take care of the water and the algae should
not be a problem. If you maintain a consistent and adequate
level of free chlorine, the need for algaecide is
diminished. Adding a
salt chlorine generator might be a step
worth taking. It is the better way to do chlorine. No
handling, no measuring product and no storage. Enjoy the
Sincerely. Alan Schuster, 5/10/2017
► Algae Control Without Foaming?
We just moved into a house with an
in-ground swimming pool. Our old house had an above-ground
pool. One of the things that I disliked about the old pool
was the foaming caused by using an algaecide. I don't want
problems to ruin the look of this pool or end up with green
water. Are there algaecides that don't foam? Willing to
Frank R., Wayne, NJ, 7/17/2004
Actually, there are algaecides that do not cause pool water
foaming. The best choices are: polymer (polyquat)
algaecides or chelated copper algaecides. The polymer
algaecides are more expensive, but are highly effective
against most types of algae. The chelated copper algaecides
are very cost-effective and are excellent in vinyl pools and
for use against the common varieties of algae, as well as
mustard algae. Most algaecides will help solve problems with
green water. While it is true that the very common "quat"
algaecides do have a tendency to cause the pool to foam, it
is not normally problematic or unsightly. In those
instances, where unsightly pool water foaming is occurring,
it is highly probable that there is an air leak in the
suction lines. A pinhole-sized leak can allow air to be
sucked in and this, in turn, leads to aeration and foam.
Something worth checking into? I hope that I have been of
Sincerely. Alan Schuster, 7/17/2004
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