Jaubert Method/Heating Cables/Laterite

I've been discussing with several people, both reefers and plant people the
possibility of combining the Jaubert Method into a planted tank.  A friend in
Tampa FL (at Marine Warehouse for those of you in that area) has just set up a
tank incorporating this design.

This brings up several possibilities and questions.

A tad of background for those who are not familiar with this method.  The
Jaubert Method involves a plenum covered by substrate.  The plenum contains
water that will be low in O2 providing an area for denitrification.  The
substrate, as I understand needs to contain burrowing and surface feeding
critters to work organic material into the substrate for eventual introduction
to the plenum area.  Malaysian snails and worms should be an excellent
substitute for the critters used in a reef tank.

This brings up several questions in regards to a planted tank.  Will the
Jaubert Method be appropriate for planted tanks?  As long as the roots are
prevented from growing into this area, and a plastic filter material should
deal with this, I see no reason it won't work.  Second, is the substrata
heating cable system really worth beans?  George you've been running one for
awhile now, can you see any real benefits.  (Guess I should add I use substrate
heating too, but am totally unconvinced of its benefits.)  The only way I can
see substrata heating systems really work is if there are temperature
differences in the substrata, ie warmer and cooler spots so a convection
current is set up.  But is this in fact what occurs?  Cables suspended in water
would do just this, but in gravel, and more especially in sand, the heat
transfer capabilities of the sand could possibly cause the entire substrate to
be heated to a uniform temperature.  In this case I do not see how this sytem
can and will work.  Any fluid dynamics or heat transfer people on the list?  If
we really want to set up a small current flow in the substrate, Claus's idea of
using a UGF plate with small heaters in the uplift tube seems to be the most
efficient at this.  We know the warmer water will rise in the uplift tube and
must be replaced.  Only way this will occur is through the substrate.  Heaven
forbid we are all wasting money when a simple cheap method would do better. <g>

Abd this leads me to laterite.  I personally have seen advantages in using this
over using a sterile gravel or sand substrate.  But OTOH I have seen much
better results using peat or top soil, and suspect plain dirt or humus would be
just as good.

What can I say, just a whimsical boring Sunday morning.  But I would appreciate
any comments on the three items above.

Doug Valverde 75051,160 at compuserve_com -or- dvalver at ibm_net