Re: under gravel heating cables -- Hypotheses vs Evidence

["Adam N." <adam at xhaos_org>]

<rant on>
This sounds all to simplified to me.  I find it hard to believe that
wherever plants grow in nature there are groundwater currents flowing.

It seems to me that at the very least there would be some sort of osmotic
pressure.  The bottom of an aquarium is plate glass on 5 sides so assuming
the water has to come in from somewhere in order to leave through the
surface the aquarium isn't exactly presenting a model environment for flow.

I also tend to thing of a river or any visible surface water and a sort of
tip of the iceberg thing.  A river or pond as I imagine it is encased a vast
hidden flow of water all around it.  The Surface water is merely what we
see.  Indeed, with a porous containment media like earth enclosing a river I
cannot readily imagine it otherwise.

I do not have the time nor the inclination to run side-by-side comparisons
but when I shutdown my under gravel in the summer the tank grows slower, but
that also has to do with the bulb replacement cycle.

Another nice thing is that you can build a DIY substrate heater really
cheap.  I like mine because it provides a little warmth all the time, if a
heater fails it's still there, the heater switch on and off less.  You can
use a smaller, less visible heater.



Adam