It will kill fish if you have any and I don't think its any good for plants if it kills the algae plant.

An Ohio State University website discusses copper sulfate for farm ponds and mentioned that it may kill some goldfish.

Gary is right, the copper will kill your fish. Clean your pond naturally with biological filtration or, try making a veggie filter.

Lorraine

I should have asked this before I did it but I put 3very sballpieces of copper in the pond and have now taken it ot. So my next question is--do I have to drain the pond and refill it or is the copper no longer in the water? Hope that makes sense. Just wonder if there is copper in the water only when the pieces are in there or is there residual copper still in there. Thanks. Not smart about this as you can tell.

I assume, since you could take it out, you had put pieces of copper metal in the water? Some houses have copper water pipes and it's recommended to not use this water for fish tanks. Some fish are very sensitive to it. If the copper was in the water for only a short time then you probably wouldn't have to worry about it. Depends on how much copper, for how long, and in what volume of water. If it was a copper compound, say like copper sulphate, then definitely you'd need to change the water.

If metalic copper has not been in the water long enough for corrosion to occur there is little chance of poisoning the fish. Remember, our water pipes have been made of copper for many years. It is a product of acidic corrosion, copper sulfate that is poisonous to the algae and to the fish. The levels of copper sulfate necessary to kill off the algae are just about the same that is toxic to most fish. The effects of the copper sulfate is dependent on the PH of the water, acidic being more reactive than alkaline. Temperature is also a variable. Different species of fish have different levels of susceptibility to copper sulfate. Koi are very susceptible as are most invertebrates.

If the copper, such as a penny has a blue residue then it has been exposed to acid and has formed copper sulfate. In a large pond a penny might not be a problem unless the fish came in contact with it or nibbled at it but why take a chance?

Other methods of algae control are better in a fish pond.

I assume, since you could take it out, you had put pieces of copper metal in the water? Some houses have copper water pipes and it's recommended to not use this water for fish tanks. Some fish are very sensitive to it. If the copper was in the water for only a short time then you probably wouldn't have to worry about it. Depends on how much copper, for how long, and in what volume of water. If it was a copper compound, say like copper sulphate, then definitely you'd need to change the water.

As others have said, most homes have had copper plumbing for many years and presumably most ponds are filled from home plumbing so there is NO danger as long as the copper was removed. One would also imagine that many people have cute metal fountains made of copper sitting in their ponds and their fish aren't dead.

Yes, I took the copper out a few days ago and just noticed 3 fish still looking pretty lively so I guess they'll survive. Well, last night I heard, for the first time this spring, the frogs are back so hopefully the fish can swim fast enough to stay away from their mouths. Thanks everyone for your help. I do appreciate it. BT

I wonder. I feel I am seeing in many places, the confusion of the element with its ions. In this case copper. The metal is copper. The stuff that kills fish is cupric or cuprous ions. Examples:

Coprous sulfate Copper(I) sulfate, Cu2SO4
Cupric sulfate, Copper(II) sulfate, CuSO4

may kill fish. Copper metal 29Cu will not. Correct?

This post was edited by albert_135 on Sun, May 12, 13 at 17:34

I believe that's pretty much it Albert. However one could imagine a too acidic and small solution with metal slowly leaching salts. And I see (wikipedia) that cupric sulfate is often used for algae prevention in waterways. I have been to a couple country auctions that had big bags of cupric sulfate. I hadn't known why they had big supplies like that.

BTW very slick HTML! How do you do that?

Will adding salt help control algae?

I also have an algae related problem in my water garden which consists of no plants or fish, but simply a lined, below ground 60 gal. reservoir which is entirely covered with a rigid screen supporting a layer of ornamental gravel. This effectively reduces the amount of sunlight on the water below. I have a hollowed out stone bowl in the center that sits on top of the gravel. Water is pumped from the reservoir up through a bamboo 'faucet' and into the bowl where it overflows and trickles down through the gravel back into the reservoir. Both types of algae form in the bowl in just a few days. I have tried one type of liquid algae control but it does not work. I don't see the need in installing a filter as I'm not concerned with fish or plant life- just algae. Does anyone have any ideas?

mrcando if you have no fish or plants is there a dye that is compatible with your color scheme? Dye is used in some reflecting pools. the ones I have read about are common food coloring dye.

Are you talking about regular food grade dye? That doesn't seem like it would be toxic enough to kill algae.

I have some of the dye that is put in pools. It's been a few years since I used it so not sure but I don't think it kills algae, if I remember right. It just darkens the water, shuts off some of the sun so algae doesn't grow. I wasn't very impressed with it. But you may have a different opinion.

Shading products, formulated and EPA-registered for aquatic use, do not kill algae or submerged plants directly but limit their growth by reducing the amount of sunlight that reaches them. The United States Food and Drug Administration approved the dyes used in these shading products for food, drug, and cosmetic color additives.

Thanks guys, I now understand the purpose of using dyes. Unfortunately, aesthetically it won't work with my Japanese themed water feature. The retailer where I bought all the components for my 'pond' discouraged me from adding chlorine or household bleach to the water because it would be detrimental to the seals in the pump. I'm now thinking of going the copper sulphate route.