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Re: Substrate Heating

>Bob wrote:
>> These actually circulate warm water through a network of
tubing...Different than other systems I have seen. A bit pricy though.
>I've heard that these don't have enough of a temperature difference to
>create the subsubstrate currents that are needed for the substrate cables
to help
>plant growth.

George Booth responded:
A long time reader of APD, Earle Hamilton, has tried hot water systems like
this. He reports he didn't see any differnece with or without substrate
heating. Two possible conclusions: heating cables don't do much (I would
argue against that) or they weren't producing enough heat to generate the
legendary micro-currents.

My .02.....
Earle's substrate heater was described in an old issue of Aquarium Fish
Magazine. It was constructed from PVC tubing. After reading the article, and
corresponding with Earle, I adapted his heater using copper tubing (regular
copper piping) to make the manifold. The manifold was painted with 3 coats
of 2 part epoxy paint, to prevent any possibility of the copper getting into
the water inside the aquarium. The water was heated in a small exterior
tank. Somewhere in the archives, I believe I posted the temperature gradient
I was able to measure within the gravel bed - it was in the range of 3-5
degrees F directly over one of the tubes vs the area between the tubes. I
found the system cumbersome to maintain (water evaporating from the heating
chamber) and the internal resistence of the tubing required a large pump in
order to get any appreciable amount of water through the manifold (too many
90 degree turns). I also didn't notice any improvement in plant growth, but
that might have been due to the soup mixture I was using as a substrate (way
too many components).

Currently, I'm using the AZOO cables sold by M3, and while they didn't
switch on last summer due to the ambient temperature in my apartment, they
are on every day now that winter is here.... Maybe I should run some
temperature readings of the substrate......

James Purchase