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Copper -- Safe?

>Date: Fri, 21 Aug 1998 12:53:07 -0400
>From: Alysoun McLaughlin <alysoun at patriot_net>
>Subject: Re: Copper -- Safe?
>> > appreciable copper exposure is of detriment to fishes and plants.
>> 3) If possible, use a small bare hospital tank for treatment!
>> - --
>> Cliff Lundberg ~ San Francisco ~ cliff at noevalley_com

>Anyway, my point was, while copper might not be *recommended*, it's not
>an instrument of sudden death, either.  At least, short-term, high
>levels of exposure for treatment, in my case, have had no visible
>effects on my plants (continued growth at the same pace, no deformations
>or discolorations).
>So there's some room for experimentation on the initial question, which
>was whether low levels would keep algae at bay vs. any long-term effects
>on fish or plants. 

many of the copper medications are designed to produce a 0.2 ppm
concentration. The initial concentration will get absorbed (adsorbed?) by
plants and other organic material. Repeated treatment and testing is needed
to maintain a desired concentration. This level will inhibit some algae,
but WILL hurt several plants (the most sensitive include Vallisneria and
fine leaved ones like Myriophyllum). More serious effects will be observed
at 0.4-0.5 ppm which can happen with repeat dosage and no testing. These
levels are used to kill various hair algae. At the higher conc., the
effects are more apparent, particularly on sensitive algae, higher plants
and animals. 

I do not believe that chelating necessarily makes it safe, perhaps safer.
Its benefit is to keep the Cu in concentration and maybe allow for a more
controlled dosing. 

Let's not forget fishes. Someare very sensitive to copper, other not.
Cyprinids will succumb with the mere mention of the word copper.... I
assume you did not have any zebra danios, or at least for long. <g>
Cichlids on the other hand are very tolerant. I have keep several species
with 0.5ppm.  There are fishes in between  who can take it to different

Same for plants. Crypts are not very sensitive, infact, some benefit from
higher concentrations. The new book by Pablo Tepoot lists the plants that
are sensitive to copper concentations greater than 0.5-1ppm.

So, the experimenting must keep track of the concentrations, duration of
exposure and the test species.

Neil Frank