Re: cables -- substrate heating cables

["S. Hieber" <shieber at yahoo_com>]

Jon Wilson noted:

 
> It doesn't have to be that hot in the tank, or that cold
> in the room. In
> the summer, I keep my house at 74 and my tank at 78. The
> cables begin
> cycling about 4 hours after the lights go off, and turn
> off shortly
> after the lights come on in the morning. 

I think Robert's point is that some setups behave like
mine.  Specifically, on my case, when the room temp is over
68F, the tank temp rises above the heater thermostat
setting of 78F during the day without running any heaters. 
Well before a room temp of 78F (the house thermostat
setting in summer) the tank gets hot enough in the daytime
that it can't cool all the way down to 78F over the
evening.  Not all my tanks are like this, but some are. 
Smaller tanks tend to shed heat faster having a greater
amount of surface area per volume.  LIghting and pumps,
etc. also have an large impact.   But heating cables won't
work (literally) on that one tank during about 4-7 months
of the year, depending on weather.  And the other tanks
don't really *need* any heaters during the warmer months.

But that is not necessarily a reason not to use cable
heaters.  Heat is still needed in the cooler months of the
year and substrate heaters are an efficient method of
applying heat to an aquarium.  Before the heat reaches the
surface and is passed off into the room, it pass up through
the tank.  Creating mild convection currents in the
substrate after several months of not doing so -- does that
kick up a lot of bad stuff that's been collecting?  I used
to think so -- I thought it was the explanation for a
problem I was having -- but now I'm not so sure.  And I am
curious about this -- if the cables runing only in winter
it don't kick up a lot of stuff that's collected inthe
substrate over the warmer months, then the roots (and
diffusion) must be doing the job Tom says they are doing,
no?

Well, heck, if I grew plants as well as George and Karla, I
might be able to tell the difference with and without
cables -- but I can't and there are too many other things
going on in my tank.

I set up two 20 gallon tanks recent and decided to make
them the same except for Eco-complete in one and Onxy sand
in the other for a short and long term comparison -- same
amount of same kinds of plants, same amount of fish food,
seame amount of ferts, same light, blah blah.  Now I wish I
had put substrate cables in one.  The 20gs are in the
basement, where the room temp is about 60-65 all year round
and a heating cable could be set up and run the way George
prescribes.  It would have been nice to run an A/B
experiment, side by side.

Scott H.

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