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Re: Aquatic Plants Digest V3 #484
In a message dated 8/31/98 12:53:12 AM Pacific Daylight Time, Aquatic-Plants-
Owner at actwin_com writes:
<< Subject: Re: Copper cpd's and plants
>>
<<
I started the copper thread with the following post: "I'm not a fan of
the text of Pablo Tepoot's wonderful new book with photographs of
aquatic plants, but one comment he made has got me thinking. He
mentions that many commercial plant growers use copper to control algae
growth. Tepoot strongly advises against this practice and regards it as
a last resort. While I'm at it let me say to the newcomers on the list
that this is a dangerous subject. I know I'm playing with fire here,
but I'm interested anyway.
What I got to thinking about is Karen Randall's reports that her planted
tanks have almost "no visible algae." I take this as absolute gospel
truth, but it's always been slightly counterintuitive to me. I have
very soft wonderful Hetch Hetchy water here in San Francisco with no
more than a trace of copper (I don't have the water quality report at
hand but there's very little copper in the water.) Karen's water, on
the other hand, contains quite a bit of copper (I forget the numbers she
posted, but it's high enough that she reduces her water changes during
copper spikes in her water supply).
For me, and if memory serves, George Booth has also made this comment
(George also has very soft water in Denver), good plant growth is
usually associated with some visible algae. It may not be much, but if
nothing else there is a bit of green spot algae to remove from the glass
at water changes every couple of weeks.
Is it possible that experienced aquatic gardeners could tweak that last
little bit of algae down a notch by the addition of minute amounts of
copper to the water column? Now for the heretical questions, if one
wanted to add a bit of copper to the water column, what chemical would
you advise? And what copper levels would be safe for our fish and
plants? I promise to be absurdly cautious-if I do anything at all!
:-)"
I tracked down my water report and my copper levels average 1.2 ug/L and
range from 1-3 ug/L. I can't remember what "ug" stands for at the
moment, but it's a tine amount of copper-maybe 1 ppb or so.
Any thoughts on my original question? Thanks. Regards, Steve Dixon
>>
Hey Steve all sorts of interesting points you bring up, lucidly as always. By
the
Paragraph:
1) Yep, many growers (all) I've met utilize simple copper sulfate or citrated
(adding about ten percent by weight of citric acid to the CuS04X5H20 to keep
it in soln.) periodically to combat algal blooms... usually post-emptively...
is this a word?)... so, I don't know if I'd quite say you're playing with
fire... but it REALLY PAYS to be super cautious in making much in the way of
declarative stmt.s on the list servs not knowing or being able to intinuate
(another made up term), who might read such and act singularly... Is this
clear? The copper used by the trade is intentionally quite transient and
generally lost in short order to more or less irreversible precipitation...
2) Love that water from Yosemites "other" valley! Methinks KarenR. may well
have a good handle on "balancing" nutrient, light availability and plant et
al. metabolism, so don't castigate yourself for being counterintuitive
(LOL)... The most the fed. EPA allows is 1.0 ppm free copper in potable water
(to the site), but this is way too much for massive (more than 20%) water
changes IMO. For me, the simplest, let's skip that and say most parsimonious
advice is to store (for a week or more) and test source water ahead of use...
3) Yep, the conditions for conducive desireable vascular plant growth are
propitious for pesky thallophytes (algae) and the cyanophytes (blue greens)...
And Geo.B also apparently has "the right stuff" set-up and maintenance-wise...
My suggestion, don't get too hung up on trying to eliminate or avoid the very
last bit of undesireable photosynthates... esp. in soft water conditions...
Copper much more toxic and tricky in such settings (WARNING Will Rogers...).
4) Yes again, it is possible, though not adviseable (by me or my kin) to
periodically admit some copper (really best as "free" copper) given all the
previous and coming provisos regarding its use. But, puhleeze, don't encourage
anyone, neophyte to the most advanced to do so... in other words, such
stooping to chemical means of algal control are not "worth it" in my opinion,
or the more appropriate technology. Look to that previously mentioned
"balance" of available nutrients (soil, water, fish foods...), light and
lighting... sufficient plant stocks (maybe some floating Ceratopteris, hmm?),
and bio-controls like your fave SAE's and Takashi shrimpathons... "It's the
system, lower I.Q. scorer" as they say.
Be all this as it may, and though there is no absolutely biologically
inocuous concentration period, most of the vascular plants and fishes people
keep can "tolerate" (emphasis mine) about 0.05 ppm free copper (or about
1.0ppm chelated depending on formulation) in most types of stock/potable
waters. Have mercy, what a lot of qualifiers... This physiological dose should
exert the desired affects: diminishing the "bad guys" w/o knocking off the
good... but, as I say, I wouldn't do it... and know of very few real aquarium
gardeners that do. Ahem, for your water and set-up, experiment with a given
stock solution and what it takes to get a reading... yes, with a good test
kit. For all lurkers/browsers and wanna-bes "Results Will Vary" with each
system and its contents... id est, the biota, other chemical species,
filtration, mulm... will interact to absord/adsorb the copper (in whatever
format), necessitating monitoring and the utmost in caution!!! For the novice,
obviously chelated copper (here's a plug for my fave: CopperSafe) is "safer"
though not as short term effective, and dangerously, more persistent... Nuff
said?
5) Looks like micrograms per liter, so you are about one part per billion; s/b
nada to worry about, even with South American knifefishes and small characoids
(LOL again)
6) Geezo, Steve, I can't even remember the original question!? The best thin
(bobaloo) about my version of "Old Timers" is all the new friends I keep
running into...
If it's okay with you, am going to spritz this over to the AGA listserv for
general grumbling and digestion.
Be seeing you,
Bob Fenner