Substrate heaters are supposed to be of long term benefit. They won't
make
your plants grow faster, better, or nicer. But they will allow you to
grow
them for many many years without getting a stale substrate.

Thanks for that. I have read in several books now about the use of
substrate heaters. In addition, I'm the type of person who reasons any
given thing out before acting. It makes very clear sense that, in trying
to mimic a natural environment as much as possible, you would like to
provide some moderate constant heat in the base, the "earth". And that
just on the face of it. In detail, substrate heaters, I'm told, create
little eddies of upcurrent or something, helping to provide circulation
throughout the substrate.




Don't take my word for it, this is just one person's opinion without
scientific experiments :-) but my guess is that substrate heaters may help
in a non-planted aquarium or even in a newly planted one. However, once
roots spread all over the fish tanks bottom most likely the benefit is nil.

--
Regards,
Marvin Hlavac
Toronto, Canada