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Re: copper in aquaria

On Tue, 23 Mar 1999, HongSungmin wrote:
> Hi all! My tank is now full of green water. I've done blanket method for
> 3 1/2 days, but nochange. Yesterday I caught some daphnias from a pond.
> Recently I've heard that 0.1-0.5ppm of CuSO4 can be a solution.
> I'm not sure if it means exactly CuSO4 or CuSO4+5H2O.
> Has anyone ever tried it? and do you think it makes a sence?

CuSO4+5H2O should do it.

There was another question recently about copper in aquariums - not
exactly the same question, but a copper question just the same.  The
archives contain quite a lot of discussion of copper in the aquarium and
you should probably take the time to read that.  In the mean time, I'll
give you my point of view.

Copper is very effective under some conditions when used as a medication
for fish parasites.  It can also kill blue green algae and green algae. In
sufficiently high doses it can also kill plants and has been used in
ponds and reservoirs for just that purpose.  It can also kill fish.

In fact, copper is an insidious poison, but it's toxicity is extremely
variable - under some conditions barely any copper will be toxic to some
species of fish, plants and algaes while under different conditions
much more copper may be harmless to the same organisms.

The difference between the copper level that is adequate to poison
undesirable organisms and the level that is adequate to poison your
plants, fish and other desirable tank inhabitants is often very small.
There is so little margin for error that copper simply should not be used
in an aquarium.

Copper is an essential element for plant growth, but it is necessary only
at trace levels and the amount of copper delivered in tap water -
particularly if your house has copper pipes - should be sufficient for the
needs of your plants.  Copper is included in some fertilizers and
hydroponic mixes where it is usually chelated.  The chelated form probably
is relatively nontoxic, but sometimes elements supplied in a safe form can
be converted in an aquarium to more toxic forms.  When selecting
fertilizers and hydroponic mixes for use in an aquarium it's important to
keep in mind that those preparations were never intended to maintain fish
and invertebrates and weren't even meant to maintain plants in complete
emersion.  Select mixes with very low levels of copper and other toxic

Roger Miller