UGH and reptile heaters

I was wondering, can anyone provide me with some info as to wattage on
undergravel heaters.  My 55 is on a stand where I can easily place a reptile
heater on the bottom glass, which would definitely provide a slow flow through
the substrate.  I am just wondering what sort of temperatures the UGH maintains
on the bottom.  Anyone have an opinion if this is a workable idea.  I just can
get a reptile heat tape really cheap.  An actual UGH would cost me more.

Working at a pet store has some advantages.

Alan Van Nevel		UMC Physics
573 882 6735
frog at theory_physics.missouri.edu

   "Animals are such agreeable friends-they ask no questions, and 
   pass no criticisms." -- George Eliot, _Scenes of Clerical Life_