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What happened to the list? + Vermiculite

It didn't come out last night or today. Maybe nobody sent anything in?

Can anybody out there using vermiculite give us any measurements on how
this affects the concentration of free nitrates and phosphates in the
aquarium water? Vermiculite is a high CEC type of clay which is expanded
to contain lots of air. When you put it in the substrate, you soak it in
water and mince it up and then mix it with the lower layer of your
substrate. Then you put a layer of gravel on top of that and add your
aquarium water *carefully*. Vermiculite provides a similar function to
laterite in that it provides lots of Cation Exchange sites (C.E. Capacity =
CEC) where positively charged ions (cations) like NH3+ and phosphate ions
will tend to be loosely bonded. There is an equilibrium that is reached
that depends upon various ion concentrations, pH, temperature etc. Now the
good thing is that these nutrients are now in a position where they can
be absorbed (by cation exchange) by the microscopic plant rootlets! This
is a wonderful thing because it means that they are NOT floating around
in solution for the algaes to feast upon!! :-)

How could we measure this effect? Well we could build a substrate just like
Jim Kelly and following his suggestions (using fairly high organic top
soil as a substrate additive!) get ourselves a pretty nice, algae free
aquatic jungle and just measure the phosphates and nitrates in the water.
We'll expect to find pretty low levels since, after all, there isn't a
problem with lots of algae. AND the plants would probably be doing pretty
good too. This is especially important if you're trying to grow Aponogeton
species which rely heavily on their root systems for an abundant supply of
nutrients. (he-he :-)

Now another idea springs to mind. What if we were to fill a cloth bag 
with a few handfuls of vermiculite (dirt cheap from that garden place :-)
and just measure nitrates and phosphates before and after heaving the
bag into a test tank. Whaddya think?

I can't try it because I've got a pretty good tank going with lotsa plants
and I'm not eager to create an algae garden in the tank with my new
Lace plants. (shucks :-) So my nitrates are pretty low and I don't have
a phosphate test kit.

I hope this stirs up a nice controversial discussion on the relative merits
of laterite vs. vermiculite. I know there's another side to the story but
I'll just wait. :-)

 - Steve