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#35565 - 06/05/06 12:04 PM Copper Sulfate and Grass Carp Kill
Bing Offline
Hall of Fame 2014


Registered: 05/03/02
Posts: 1622
Loc: Fayette County Illinois
I have a 50 year old three acre aireated pond. It is about 18 ft. deep in the deepest. The aireation system has been in place since mid-year last year and until about two weeks ago was doing a great job of controlling the FA. Two weeks ago FA just seemed to appear overnight and there was enough of it, and about 15% cover of Duck Weed that last Saturday I spread 50# of Copper Sulfate (this is the amount I have used several times in the past). I trailed a gunny sack in the water and made one complete circle of the pond and felt I got a fairly even distribution.

Surface water temperatore is 78 to 80 degrees.

Yesterday afternoon a found a 24# grass carp dead. Another one this AM. Looks like I messed up big time. I am not overly concerned about the grass carp (I stocked 11 of them about 5 years ago and I have never been convinced they helped any), however I am quite concerned about other species, especially Blue Gill and Bass.

The good news, I hope, is that yesterday AM I caught a 1# bass and last night I caught 5 more between 1.5 and 3#. They were very active in shallow water in the shallow part of the pond where I found the first dead carp. Since I have a relative who is restocking I held the morning catch and combined it with the five in the evening and he picked them up last night. I tell this part because the bass were active last night and one bass did well in my rabbit hutch cage in 5 ft. of water all day. I view this as a hopeful sign.

Did I poison the Carp, or create a low oxygen level? The dead carp were found in separate coves in the shallow end of the pond.

Any ideas, specifically I am interested in knowing if there is any course of action I can take to minimize the problem. I am running the aireators about 12 hours a day. If the problem is DO will this help? Should I run them full time?

I have four shallow diffusers and one in deep water. I have shut off the deep end one, thinking originally that it would keep the Copper Sulfate in shallower water, and now thinking that bringing up the deepest water will not be particularly helpful if indeed I have a DO problem.

Any suggestions would be appreciated

"I love living. I have some problems with my life, but living is the best thing they've come up with so far." Neil Simon,

#35566 - 06/05/06 01:46 PM Re: Copper Sulfate and Grass Carp Kill
ewest Offline
Hall of Fame 2014


Registered: 03/08/05
Posts: 19833
Loc: Miss.
Copper Sulfate ( CuSO4 ) can cause problems in a number of ways.

One is quick death for fish and lasts a day or so. It happens most often with low alkalinity and CuSO4 combined. It causes the fish's gills to be unable to uptake oxygen and thus a quick death like a DO kill.

A second problem is longer in the making but can kill the entire pond. This occurs when a large area of the pond is treated for weeds , the weeds die as well as the plankton , they not only quit making o2 but as dead plant material uses up the o2 in the decomposition phase you get a full blown DO crash.

Yet another problem is the build up of copper from multiple uses in the pond bottom soil which can be toxic as well.

Still another problem is the effect of treating with CuSO4 when the fish are spawning with eggs/ small fry /yoy as they are much more susceptible to its effects.

GC are less tolerant of CuSO4 than some other fish.

Chelated copper products are much better. If you use CuSO4 learn about its effects first.

See this fact sheet from SRAC:


See these with emphasis on Bill Cody and Kelly Duffie's posts :



#35567 - 06/05/06 03:01 PM Re: Copper Sulfate and Grass Carp Kill
Bing Offline
Hall of Fame 2014


Registered: 05/03/02
Posts: 1622
Loc: Fayette County Illinois
Ewest, thanks for your prompt reply.

In the short term, at least, it looks like I may have dodged a bullet. Just did an inspection and a little fishing at lunch. There were lots of small fish in shallow and deeper water. I fished with a Storm King Bitty Minnow, which is pretty effective for bluegill and bass. I use the very small one with an ultralight. It must be 1/8 oz. or so. The smallest crank bait I have ever seen. Caught a 1.5# LMB on the first cast and two or three 6 to 8 inch bluegill. Nothing seemed to be stressed.

Not to overreact to ewest comments, but I have studied CUS04 fairly extensively in the past. This is the first time I've experienced a problem. I used Cutrine + a couple of years ago with practically no success. I don't know my water's chemistry so that may have been why Cutrine + was so ineffective. I even called the manufacturer to get their intrepretation of the formula relative to the size of my pond and applied it in the consentration they recommended.

Obviously anytime you use a caustic substance like this there are risks. This time a think I pushed the risk factor a little too far.

Ewest, I have not read all of the threads you posted so I am not sure if any addressed the long term effects with any scientific evidence. The last time i researched it and my informal discussons with Pond Boss staff and others indicate the long term effects are not well established. I have a fairly fertile fishery which has been in my family since we built it in 1954 and I shutter to think how much CS has been applied. Of course, that is one of the reasons I had the aireation installed last year.

"I love living. I have some problems with my life, but living is the best thing they've come up with so far." Neil Simon,

#35568 - 06/05/06 03:28 PM Re: Copper Sulfate and Grass Carp Kill
ewest Offline
Hall of Fame 2014


Registered: 03/08/05
Posts: 19833
Loc: Miss.
Bing try this one from one of the links.

Bill Cody
Member # 24

Member Rated:
posted September 03, 2004 11:14 PM
My data base for total Cu in the hydrosoil(sediments) is still relatively in the beginning stages. I have not kept up with sampling for that type of research anymore. My data is mostly from the early 1990's when copper sulfate was used extensively around here in NW Ohio. It is still used a lot but due to my "preaching" and intensively "spreading the word". As a result it is not used and recommended as indescriminately at least locally as it was in the past.

The concentration that you found in the hydrosoil seems somewhat low from my experience for a pond that has had frequent use of CuSO4. Ten to 20 yr old ponds, up here in the limestone-clay based soils that have had frequent moderate to heavy doses of CuSO4, have total Cu concentrations that range from 100 to 500 mg/Kg in the hydrosoils; some at even a little higher levels (measured w/ flame atomic absorption).

Sediments under these extreme Cu conditions are for practical purposes, basically dead and I could not find benthic invertebrates or active bacteria present in any of those sediments. In ponds with our typical limestone soil chemistries, experience has shown that, once the Cu concentration in the hydrosoil accumulates to around 400-500 mg/Kg (800-1000 lbs/acre) much of the copper from new additional treatments will remain dissolved in the water column and does not percipitate. It "appears" that the sediments are "full" or saturated with Cu and new copper additions "hesitate" to percipitate out of the water as usual. Thus the water column contains free Cu ions sometimes at concentrations of up to 2 mg/L that persist for extended periods. Length of persistance "seems" to depend on variaables including the application rates & time since the last CuSO4 treatment.

At Cu concentrations of 7 - 10 mg/Kg in the pond sediments around NW Ohio, I have collected a few living invertebrates such as oligochate worms, nematodes and a few larval insects (rarely burrowers). I am not real sure of the concentration of Cu where the invertebrtates are completely eliminated. It is no doubt on a gradual scale that is affected by the buffering capacity of the hydrosoil and the sensitivity ranges of the many different species of invertebrtates that inhabit the pond bottom. As the copper levels increase, more and more types of benthic invertebrates are probably eliminated from the habitat, with the most Cu sensitive dying first and the most tolerant dying last. Invertebrate reproductive capacities and growth or development of egg through instar stages are also probably affected by the abnormally high Cu concentrations.

As far as I know, very little in-depth research has been done with high concentrations of Cu complexes in teh hydrosoil. Numerous Cu toxicity studies have been reported in the scientific literature but they did not test the real high Cu concentrations that we taking about and at concentrations that are no doubt present in numerous, chemically, mismanaged ponds.

Copper Remediation. From my experience very little can be done to remediate these high copper concentrations in the hydrosoil. Nature's law -- Copper is a heavy metal and heavy metals are stable in the environment. Copper is now on at least three governmental agency lists (USEPA, CERCLA & SARA) as a priority pollutant or hazardous/toxic chemical. In the future as more of its affects are studied we will earn more about its impact and long term affects in the pond system. We have had some success percipitating the persistant free copper ions out of the water column with lime and alum treatments in order for "normal" phytoplankton and zooplankton communities to redevelop.

Natural coppper concentrations in the hydrosoil of some lakes has been studied and it was discovered that under certain conditions copper will redissolve from the sediments and enter the water column. This was found to occur primarily during fall turnover or destratification.

[ September 05, 2004, 09:20 PM: Message edited by: Bill Cody ]

#35569 - 06/05/06 11:04 PM Re: Copper Sulfate and Grass Carp Kill
Bill Cody Offline
Field Correspondent


Registered: 04/18/02
Posts: 12804
Loc: Northwest Ohio - Malinta OH
Postscript to my post above. The state of Washington no longer allows the use of copper sulfate for algae control in pond and lakes. In the future, other states will follow their lead.
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#35570 - 06/05/06 11:16 PM Re: Copper Sulfate and Grass Carp Kill
Tuzz Offline

Registered: 08/17/03
Posts: 235
Loc: Greenfield Park, NY
We too are having a FA problem this year in New York. Very low snow fall and very dry spring made for little to no spring run off. The past month has blessed us with above average rain and that witht the wife and I manually removing the FA with a net as we kayak the shore lines seems to be starting to get ahead of it. My concern is that when the summer heat and dry weather hits we are going to be in trouble. I have been trying to avoid chemical control and this post makes me feel stronger about avoiding it. What are we do try???? We need some of you experts with long term experience to contribute on this one.

#35571 - 01/25/07 04:36 PM Re: Copper Sulfate and Grass Carp Kill
magic1234 Offline
Junior Member

Registered: 09/18/06
Posts: 7
Loc: ct
did you try copper sulfate that might clean up your problem


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