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topic 9128 p3

Copper Sulphate as Swimming Pool Algae Remedy?


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A discussion started in 2001 but continuing through 2019

January 14, 2018

Q. After a few months of clear water with copper treatment, I am now having a bloom of a copper resistant green filamentous algae. My copper concentration is 0.4 ppm as determined by the LaMotte 3619 Copper Test Kit. pH is maintained under 7.4.

It's been going on for a few days now with no sign of abatement.

I do have a residual, from the previous Chlorine system, of 150 ppm Cyanuric Acid, i.e. stabilizer. Also when I a add more copper sulphate, I don't see a rise in concentration beyond the 0.4 reading which has me puzzled. Could it be the residual CYA?

I read about a copper resistant green filamentous algae so I guess I have it.

What should I do?

John Stranahan [returning]
- Miami, Florida USA


January 17, 2018

A. Sounds like you've got a nasty algae there.

First off, I'd reduce pH to 7.2 or 7.1 This will make the copper more soluble and more effective.

Then I'd hit it HARD with chlorine, calcium hypochlorite, until you get up to 4 or 5 ppm which stays up overnight. If you pool is heavily infected, you will likely have to make multiple adds over a few days. If yours is a typical 16' X 32' pool, you might end up using 5-10 pounds or more of hypochlorite. As you kill it off, keep back washing your filter to get rid of the dead stuff.

Consider NOT using CNA. In my opinion it causes more problems than it solves.

You CAN kill it.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina


January 17, 2018

Rereading your post - "the previous Chlorine system".

By this do you mean that you entirely stopped the use of chlorine and relied only on copper?

If so, that's wrong. Copper is highly effective against MOST forms of algae, but not all. And copper is ineffective against other possible nasties - bacteria, viruses, odors and others.

Chlorine is absolutely a necessary component. It should be abt 1 ppm at all times, with an occasional boost to 2 or 3 ppm.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina


January 20, 2018

thumbs up sign Solved for the time being.

Thank you Jeffrey for your interest and comments.

This situation came about from the pool owner (I've offered to help her with the pool care) having used trichlor tabs exclusively for chlorine titer. Like with so many that I have read about online, the cyanuric acid (stabilizer) in the tabs builds to problematic concentrations. It remains as the chlorine diminishes. She is adamant about not draining half or more of the pool to reduce the CYA concentration. At the present concentration of 150 ppm, chlorine action is reduced dramatically, requiring very high chlorine concentration for control.

Since the pool is solely ornamental during the winter and since it is only she who uses the pool occasionally in the summer, pathogens are of no concern now and human contagion never.

So I thought that I would give "copper only" a try by using copper sulphate as available economically as root killer at Home Depot and Lowes. At 0.3 to 0.5 ppm copper it cleared the pool of algae after Hurricane Irma and did well until I got a copper resistant strain a few weeks ago. It is consistent the online description of the copper resistant Pithophora, a green filamentous algae.

Knowing that copper is allowed in drinking water up to 1 ppm I decided to see if I could get some algaecide action at 1 ppm since it is still safe for humans at that level.

After three days at 1 ppm copper the pool is now clear. The plan is to now maintain the copper concentration at or a little under 1 ppm.

When the season rolls around for her occasionally using the pool I will sanitize it to 1 ppm chlorine for pathogens.

So for now all seems to be in order. I've read the warnings about the black stains resulting from chlorine copper interaction but that is to be seen or not.

BTW, the patches of black algae on the pool wall have disappeared since using copper sulphate, without any scrubbing.

John Stranahan [returning]
- Miami, Florida USA


January 19, 2018

Q. I have now used Aqua Pro 'Algaecide' 2 liters in my 63000 liter pool, it is clearing up and getting blue again. My question, however, based on the previous posts, is whether one can maintain the Algae with the 'Copper sulphate' powder one can buy at the Chemist. Can anyone advice how much to use and timetable?
Thanks

Manfred van der Brugghen [returning]
Construction Professional - South Africa, Johannesburg


January 20, 2018

A. Maybe you can use plain copper sulfate, but it's solubility is limited. IF you keep your pH on the low side, say 7.1, it may be soluble enough.

Much better to buy chelated copper sulfate based algaecide which is freely soluble. It doesn't need to be expensive since it is essentially permanent, being lost only when you remove water.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina


January 20, 2018

thumbs up sign Thanks Jeffery, will give it a try.

Manfred van der Brugghen [returning]
Construction Professional - Johannesburg, South Africa


January 31, 2018

A. In fact, Copper Sulphate is very easily soluble. Prior to dispersing into the pool water it is good to add half of a cooking ladle of CS (ca. 150 gr) into a bucket with water (ca. 10 l), and mix it. Then, taking out continuously the dispersed solution from top and distribute it into pool while filling up more water into bucket and mixing, taking out again, etc., until all the blue powder is dissolved.

Jan Mrskos
- Lampang, Thailand



May 17, 2018

Q. After deliberately increasing the copper concentration to 1.4 ppm to kill off a resistant strain of algae I now need to reduce that concentration to below 0.5 parts per million to get the pool ready for swimming season.

What I am looking for is a low-cost method of decreasing the copper concentration. Methods available via pool supply stores cost over $100. I'm hoping to find something lower in cost and PROVEN to work in swimming pools with common pool filtration systems. Any information on this would be greatly appreciated.

Jon Stranahan [returning]
- Miami, Florida


June 23, 2018

A. We have an 18' round 54" deep above-ground pool. Every summer we only buy three things …

We already have a small box of copper sulfate we bought at our local tractor stuff store. We mix 1-1/2 cups of the bright blue granules in a 5 gallon bucket of clean water. Stir until all grains are dissolved. We walk the perimeter of the pool in the afternoon and pour all of the mixture in. Then (here's what we buy) we walk around again pouring 5 gallons of HOUSEHOLD bleach. The cheap stuff works for us but don't use laundry bleach. It has less chlorine in it. After adding 2 chlorine tabs (3") to the floaty thing. We wait usually 2 days with the pump on full time. Backwash and rinse our sand filter 2x per day.

By then the water is blue but still can't see the bottom. A trip to the "garden and pool" center at the local WALL place for a bottle of clarifier. This coagulates (clumps together) the now dead algae and brings it to the surface so the filter can more easily filter it out. We walk around the pool pouring straight from the container about half of the thick blue liquid. Again keep the pump constantly running. A day or two later we can usually see the bottom and all the muck. Once we vacuum, this stirs up more stuff (we vacuum while in pool) after that we use the rest of the clarifier in the same manner as before.

Don't get in the pool if the water is green. This could be live algae and getting it in ears, nose or mouth could cause problems. Don't use any more copper sulfate. You can test it if you want but we find our measurement works for us. We only use one dose of copper sulfate upon opening the pool. Only once did we use it twice because we had a very very rainy summer, weren't in the pool often and let the chlorine tabs run out. We haven't had any blond haired beauties turn green on us. We don't use shock either. If you use too much clarifier it could make pool a "white" cloudy. But it will filter in a few days. We are usually vacuuming at 4 days and are swimming about 7 days after starting the routine. We use the recommended dose on the box of copper sulfate for the gallons we have. Use the internet to figure your gallons if you don't know. Have been using this in our above ground with the original liner for 15 years. We do have a sand filter but no ionizer or UV filter or heater. So I don't know if you should use with these. Hope this helps.

Judith Brewer
- Hohenwald, Tennessee, USA


July 2, 2018

Q. My situation: Hi, we used copper sulfate in our 27' round, 4 1/2'deep pool. My question is, what can I use to raise the hardness, total chlorine and free chlorine? They are all showing 0 on my test strip and I don't think I can use shock.

Jan George
- Tyrone, Pennsylvania


July 8, 2018

A. No worry about Copper Sulphate, the pentahydrate (CuSO4·5H2O), the most commonly encountered salt. Copper (Cu) is allowed e.g. in German standard for drinking water up to 2 ppm. And Cu is contained in CS just by 20 - 25%, i.e., with 8 - 10 ppm CS you get 2 ppm Cu.

During next days the Cu is depleted by reactions with algaes and other unwanted substances in pool water, hence it will be filtered out, backwashed and vacuumed from pool bottom.

And/or farther dissolved by rainwater, by additional water after backwashing, vacuuming.

After CS dissolving it is better to stop the pump and let the CS work. When later added a flocculant (e.g. Alum - a wonderful substance formerly used by our fathers for stopping bleeding after shaving), all will sink to bottom.

BTW, the algaes are not harmful, they just keep the water from being crystal clear, beautiful for our eyes.

Jan Mrskos
- Lampang, Thailand



November 16, 2018

Q. Hi. I need to know how much Copper Sulphate to add to drinking water to remove Algae and I believe any protozoans or coliform bacteria which I also believe are sensitive to CuSO4?
My storage tank is 5000 Litres.
i.e., how many grams to 5000 Litres.

Many thanks.

Jean-Pierre FOURIE
- Harare, Zimbabwe


November 2018

A. Hi Jean-Pierre. Garry S claimed that 1 ppm ^ copper is quite safe, and estimated that ^ at 0.5 ppm 100-120 grams ^ copper sulphate would be required for a 50,000 litre pool (meaning 10-12 grams ^ copper sulphate for 5000 litres). Jan M says 2 ppm ^ copper is safe per German drinking water standards. The USA EPA limit is 1 ppm ^ copper. WHO seems to accept 2 ppm but lean towards 1.

This should cover it if you're talking about your own family's drinking water. If you have responsibility for someone else's I think you need to work on a deeper level with regulatory agencies.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


November 17, 2018

Ted Mooney, P.E. RET

thumbs up sign Thank you so much for that information. That's exactly what I required. The promptness of the answer was impressive. Thank you again.

Jean-Pierre FOURIE [returning]
- Harare Zimbabwe


November 19, 2018

Comment:
The 1 or 2 ppm is a limit of Cu for drinking water. Since CopperSulphate contains only 20 - 25% of Cu, the limit for CS can be 4 - 5 ppm (when Cu 1 ppm), event. 8 - 10 ppm (when Cu 2 ppm).

Jan Mrskos
- Lampang, Thailand


November 2018

thumbs up sign  Thanks, cousin Jan. Garry S suggested 0.5 ppm of copper for algae control and said that it equated to 100-120 g for a 50,000 liter pool and his calculation was correct and based on your copper percentage of 20-25%. For Jean-Pierre's 5,000 liter water tank, that would scale down to 10-12 g, so hopefully we gave him the answer he sought.

But you are correct that my posting was confusing in 2 ways --
-- not making clear which numbers referred to copper and which to copper sulphate (which I have now repaired with superscripts, and
-- reverting to Garry's 0.5 ppm of copper for the calculation while saying 1-2 is probably okay. Thanks for the catch.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha



February 14, 2019

Q. I have just started to use copper sulphate to try to keep my tile joints clean after spending 4 days cleaning them by wire brush and gaining aches and pains in the process. I note that people are talking in terms of PPM, but how is this measured? Is it simply the number of grams of CS granules divided by the total number of grams of pool water x 1 million?

David Ballinger
Retired civil engineer - Pattaya, Thailand


February 2019

A. Hi David. You are right about PPM meaning parts per million, but uncertainty is introduced when you ask a 3rd party what someone else meant :-)

Some people might mean parts per million of copper (Cu), others might mean parts per million of copper sulphate (CuSO4), and some might mean parts per million copper sulphate pentahydrate (CuSO4·5H2O = weight of the crystals).

Copper sulphate pentahydrate is 25.5% copper by weight, so if you want 1 PPM of copper you need to add 4 PPM of crystals. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


February 15, 2019

thumbs up sign  Thanks to Ted for his very quick response to my query. An on-line pool supplier in Thailand recommends that CS should be added at 3 gm per cu.m. of pool water. A cu.m. of water weighs 1 million grams so based on the above recommendation the proportion of CS in solution will be 3 parts per million, producing slightly less than 1 ppm of copper. The recommendation goes on to say that this treatment should only be done twice per year to avoid build up of copper with its undesirable side-effects.

David Ballinger [returning]
- Pattaya, Thailand


February 22, 2019

A. Once you are frequently backwashing the filter and vacuuming the bottom (I do it mostly in one go) you have to add fresh water. Consequently, the concentration of the Cu is slowly reduced. And that beside the fact, that the Cu is also diminished by reacting with the algaes. Therefore a timely addition of a new CS portion is needed, especially in the springtime.

As a matter of fact, when e.g. the German standards for drinking water allow 2 ppm of Cu, the 2 ppm in the water for swimming should not make any harm, even if it is a bit over. The 2 ppm does not mean that a tiff or two of it is poisonous, the value is for a precaution if it would be permanently drunk over a longer period of time.

With treating the swimming water by CS we spare ourselves of the daily hassle with keeping a high level of chlorine (to kill the algaes) and also of the difficult (and expensive) job of maintaining of the pH, that is for the chlorine effectivity important but not for the CS.

Jan Mrskos
- Lampang, Thailand



Citric acid as chelating agent in swimming pool

May 22, 2019

Q. Hi I read that you can use citric acid as chelating agent -- what would the ratio be? I have a 50 000 ltr pool. Pardon the ignorance but what does the chelating agent do, and will it not diminish the effectiveness of the copper sulfate. Thank you.

Rassie Erasmus
- Amanzimtoti Kzn South Africa


May 31, 2019

A. Rassie,
In chemistry, metal ions dissolved into water carry a positive charge, because they are missing electrons compared to their solid metallic state. This means that other ions with negative charges like to stick to them. When this happens, it's called a ligand. The more electrons "missing" from the metal ion, the more ligands can stick to it. Similarly, some negatively charged ions carry multiple negative charges, and some of these are structured in a way that they can sort of wrap around the metal ion and act as several ligands all in one molecule. When this happens, the ions stick together much more strongly than with individual ligands. This is known as chelating, taken from the Greek word for claw, because it sort of looks like a claw gripping the metal ion.

However, I don't know how this specifically applies to a swimming pool. If you're using copper as a disinfectant, I'm guessing you don't want it chelated because that might protect the germs from the copper. "Chelation therapy" is one method used to protect people that have swallowed toxic metals.

ray kremer
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
stellar solutions banner


June 4, 2019

Q. Thank you Ray: Read that chelating the copper sulfate with citric acid slows the process down and would give you more control over its use as disinfectant(algae) in pool water treatment.would I be wrong in thinking that the chelating of the copper sulfate would keep it in "suspension" until needed.Treated a friends pool with Gary Sutherland's formula after he spend hundreds on pool chemicals (so cheap,did it for free.lol)Problem is I now have friends I don't even know but do recognize the fact that misuse of the copper sulfate is dangerous. The pools I have treated shows levels of 0,80 0,5 and 1,0 and according to local pool companies the acceptable level is 0,2. Any further advise on the use of copper sulfate for pool treatment would be apreciated. Thank you

Rassie Erasmus
- Amanzimtoti Kzn South Affrication



June 27, 2019

Q. Hi Everyone, We have a concrete 90 year old in-ground pool. It is approximately 84,000 gallons.
Our care is to drain the pool in the spring and wash down the sides and bottom with power washer. We fill the pool from the spring.

This has always worked, but last year and this, I had 2 high school boys drain and clean. When the pool filled, it was slightly green and cloudy. I shocked it, but it didn't help. This year, again the same problem, but the algae is worse. I triple shocked and nothing. I am going to use copper sulfate, now. I think that the pool just wasn't cleaned properly. I had always power washed scrupulously in the past. WE HAVE NO FILTER. Water runs into pool from a small warming pool. Water can be diverted to pond to somewhat warm the big pool. Our pool is so untraditional that I simply can't find any solutions. There is no electricity down at the pool about 200 yards from the main house. Any thoughts truly appreciated. Also, My usual treatment was to toss in a couple of cups of granular chlorine, every other day. This kept the pool clear and when water diverted to pond; the chlorine dissipated and didn't harm fish. I ran this by our local fish and game and they said the sheer volume of water in the pool mixed the chlorine with little harm to the fish, frogs, etc. in the adjacent pond. Thanks to all.

Frannie Stone
- McDonald, Pennsylvania, USA



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