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surface area of clay and crushed fired clay

Once clay has been fired into ceramic form, it is essentially rock
because it has fused. Clay is any rock material which has been crushed
to smaller than 2 microns in size. Sand particles at 2 mm diameter are
thus about 1000 times larger in diameter than clay particles of 2
microns. This means that 1 pound of clay has about 1 billion
(1,000,000,000) times the surface area of 1 pound of sand (or crushed
fired clay with average size of 2 mm) Clay can be much smaller than 2
microns too!

Mineral diffusion from a fused material such as crushed ceramic (fired
clay) will be much slower because of the smaller surface area of

I made a typo in my last posting; I meant to ask Greg about the possible
organic content of Fluorite not laterite! OOPS! :%)

My speculation (guess) at the composition of Fluorite is based solely on
the premise that a "good" substrate -might- contain all macro and micro
nutrients in appropriate dosages. As for calcium, you might be reasoning
that it should not be present because it would necessarily be in the
form of a carbonate salt which would raise the pH. It could also be in
the form of a sulphate which has lower solubility (I think) which won't
have much effect on pH. I'm not at all sure that one could depend upon
the substrate for adequate long term supplies of K, Ca and Mg. On the
other hand, adding those minerals to a prepared substrate material would
be easy and might have benefits especially if they were not supplied
adequately in the water as is often the case with potassium.

It should also be obvious that N and P in the substrate are also used up
and would need to be supplemented in some form (fish food, fish poop,
nitrate salts in solution, ammonia salts, lawyers or cats or various
animal spoor)

It's just guesses. Only the folks at Seachem or any analytical chemists
in the employ of the competition, know for sure. They could even have
other things in fluorite of a more complex nature such as organic
materials to help in the reduction processes, and root hormones.

Has anyone ever tried using a root hormone with aquatic plants? I recall
someone using gibberelic acid to stimulate flowering of emerse Crypts.
Gibberelin produces interesting results when fed into a web search
engine. (sort of like nitrous oxide ;-)

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!