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re: iron testing

Tom Barr wrote:
"I tried using SeaChem's traces(no iron) and did not have the best luck with
the plant health. The sub was flourite so there was plenty of iron from that
source but the plants seemed to suffer even when adding a fair amount of the
other traces in there. We certainly need liquid iron at high CO2/light
levels. I think you can do without this at lower levels of CO2/light and non
CO2 tanks though."

First of all, how long had this tank been up and running? While we know the
elemental constituents of the mineral/clay Flourite is made of, we have
absolutely no idea how bioavailable those constituents are. Over time, as
organic acids accumulate within the substrate, certainly many might become
available at some rate but what that rate might be remains a mystery.

I agree that high light + injected CO2 presents a totally different set of
circumstances to a low/moderate light tank with no CO2 injection. But from
the information in one of the articles I listed earlier, it is quite
possible that adequate CO2 is more important than high light levels.

"IMO adding what folks are adding(to 0.1ppm) and basing it off a residual
test for iron is not telling you the whole story here about your plant's
needs or uptakes."

That's all well and good, and quite possible true. Iron is apparently only
used as an indicator of overall trace element levels and availability. How
much they (the plants) need depends on how much light and CO2 and the other
essential elements are available to them. Someone with a low light, non CO2
injected tank who follows your recommendation for 1.0 mg/L of iron might be
in for a very green Christmas.

"You need more traces than what your kits are telling you. Plants are the
best indicators for this, not the kits, at least from what I've seen. We can
go back and figure out the "whys" and "what did we miss" later."

Now, this I have a bit of a problem with.Upon what, other than personal
observation in your own tanks, are you basing this recommendation? I'm not
necessarily saying that its not true, I just prefer to put my trust in
sources which base at least some of their recommendations upon objective
experimentation and observation. That is why I and so many others admire the
work of people like Diana Walstad. We may not maintain our tanks in a
similar manner, but her use of quoted reference material and objective
experimentation with reported results give us sufficient information to
reach our own conclustions. You seem to expect us to just take your word for
it. Worry about the why's and how's later.

Sorry, neither science nor nature works that way...... not even in

James Purchase