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Re: Substrate idea and water quality questions



> But I can't find any of this clay for sale on their web-site.  Maybe it's
> there and I missed it.  And what hydroponics growers specialize in is
growing
> terrestrial plants in an aquatic environment.  I still think they must
have
> something to offer us since we are using the same basic medium.

I can't see it in their price listing either, but I would assume that they
carry it in their stores and could quote you a price if you e-mailed them. A
lot of small companies don't have their complete stocklist online yet. One
thing they do list, which could be very interesting, is Grorox, an expanded
clay substrate in 2-4 mm sizing. It is not perfectly spherical and from the
photos on the website it might be a good choice for a substrate/additive in
a planted aquarium.

There is a big difference between growing plants hydroponically and growing
them submerged. Access to CO2 is greatly complicated for submerged aquatic
plants. Just because products will work in one application doesn't mean that
they will necessarily perform in a similar fashion under different
circumstances. The presence of live fish in most aquariums further
complicates things because you have to be sure not to add anything which
could prove harmful to them, regardless of how good it might be for the
plants.

> >  Clay in a substrate does help to bind nutrient ions until they can be
> >  absorbed by plant roots. I don't like the idea of the presence of
almost
> 23%
> >  aluminum in this stuff - that could present you with toxic conditions
once
> >  submerged. Dupla, in their many writings on laterite, stress the fact
that
> >  laterite is a type of soil which has has most things (which could
present
> >  problems) leached out of it.
>
> But one of the things that is not leached out of laterite, as I understand
> it, is the aluminum.

True, and as I'm not a Geologist I may be going out on a limb here (and if I
do, I'm sure that someone will come forward with a saw to cut me free...) -
on the website they stress the weak bonding of this type of clay - when wet
it just falls apart. My fear is that the aluminium might be released from
the clay matrix and be absorbed by the roots of the plants in sufficient
amounts to cause problems. I don't know if this would happen, but it might.

> Or maybe I could just grow some plants in the stuff and see how they do.
If
> I want to get all scientific with it, I'll pop the tuition and go back to
> school.  I'm trying to have fun here, remember?

Actually, some of us enjoyed school, and the scientific investigations which
the facilities there allowed us to conduct... but if that's not your thing,
no sweat - it was only a suggestion. Its the same old argument - "Someone
should run some tests.... someone _else_..."

> This is a small town, with small town ways.  Last year the color was
reported
> in TCU, but the secretary for the water dept. had a baby.  The new
secretary
> probably got cruising along and didn't notice.  I didn't think about it,
or I
> would have corrected it myself.

In that case, I would suspect the entire analysis of your water supply. Such
laxity in the Civil Service, even in a small town, is not very heartening.
But then again, I tend to take my responsibilities seriously and demand that
my staff do the same or look for alternate employment - like at McDonald's.

> Which is part of the reason I don't want to strip this stuff out.  The
other
> part is that I am renting a very small duplex and sharing it with my four
> kids.  There really isn't a lot of room for dealing with such a set-up.
And
> if I can avoid the waste-water issue, all the better.  This is the West,
not
> the Great Lakes Drainage, and water out here is precious.

Yes, I guess that those of us who happen to live next to one of the largest
resevoirs of freshwater on the planet tend to take it for granted sometimes.
But that is no excuse to waste it. Most municipal water supplies are
perfectly suitable for aquarium use with only minor adjustments. My
suggestion was made simply because you have a particular vision in mind (low
conductivity South American biotope) and your knowledge of the water
parameters you currently have seems spotty at best, due to possible problems
with the accuracy of the report you are working with. Trying to make
adjustments and or corrections in such a case can sometimes prove futile and
it is sometimes just easier to start with a blank slate.

James Purchase
Toronto