Re: Under-tank heating coils.

> From: Kevin Conlin <kcconlin at zola_cae.ca>
> I get pedantic when speculation on my part (about the possible
> equivalency between under-tank heating and substrate heating coils)
> gets vehemently refuted with what turns out to be more speculation
> cloaked in science and engineering terminology.

Perhaps Canada has a different definition of "vehement" than I do or 
I forgot what I or others wrote, but I wouldn't call this 
discussion vehement.  (Thanks, I don't need a definition at this
> From this thread it would seem that
> there is no definitive answer at the moment.

That is true.  We are taking Dennerle and Dupla at their [advertising]
word that coils are the best way to do this.  We don't know why coils
are best.  We don't all the ins and outs of what coils are trying to
achieve beyond my speculation and 4 years experience with them. 

> Some people are going through a lot of trouble to design DIY substrate
> heating systems.  I imagine they might be rather ticked off if they found out
> later that they could have achieved comparable results with a simple
> and inexpensive under-tank heater.  

They will also be ticked off to discover they have no way to determine
if their design works at all, if it is the same as coils or better
than coils.  Most of the "designers" of alternate schemes don't seem
to understand what substrate coils are trying to accomplish (present 
company excepted).  Most haven't considered how to test what they 
have proposed.  

I have found that a plain old substrate will do great for 18 months
(in one particular case) and then plants will begin to do "poorly".
Since a typical aquarist seems to keep changing their focus, they may
have a plant tank do well for 6 or 12 months before they tear it down.
They will probably conclude that their alternate design "worked" and
they will endlessly promote their [possibly bogus] ideas.

I have also found that a substrate with heating coils works somewhat
"better" for at least 4 years (so far).  I therefore conclude that
coils DO NOT help plant growth to any great extent but promote long
term SUSTAINED growth.  I conjecture that this is due primarily to
fresh nutrients being brought into the substrate by slow convective
currents.  I conjecture that coils are the best way to do this.

This is all argument based on conjecture.  I am happy with coils.  
I try to promote their [possibly bogus] effects based on my
experience.  If you want to do something else, do it.