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Re: Do substrate heating coils fertilize the substrate?

>Date: Fri, 23 Oct 1998 11:09:56 -0500
>From: "David W. Webb" <dwebb at ti_com>
>George has pointed out for years that his plants grow better in tanks with
>heating cables than those without, and that the heating cable tanks last
>longer between teardowns than those with plain substrates. 

You've done a great job summarizing my stuff while I was distracted
elsewehere. Thanks for helping with the discussion. I wish I could jump in
during the day but my employer is clamping down on non-work-related e-mail

However, I hope I've been careful to point out that, IMHO, heating coils DO
NOT give you any faster growth, just a more stable tank. Presumably because
the substrate is kept "fresh" by an unknown mechanism. If I *did* write
"faster growth" and it's in an archive somewhere, point me to it and I will
try to correct it.   
When we had the 100g tank and the 90g tank set up (mentioned in your later
post), I could NOT tell any difference in the growth patterns between the
tanks at first. But after 18 months, as you mentioned, the non-coil tank
started to slow down.   

>Transpiration occurs, carrying water and nutrients from the roots to the
>Heating cables warm the substrate and thus, the roots.
>Warmth increases metabolism.
>Increased root metabolism means faster root growth.
>Increased root metabolism means faster transpiration.
>Faster transpiration means more water and nutrients move from the roots to
>the leaves.

So I have to take issue with your conclusions. Perhaps the heat causes more
transpiration, but it would not be related to faster growth. IMHO.

George Booth, Ft. Collins, Colorado (booth at frii_com)
  Back on-line! New URL! Slightly new look! Same good data!