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Re: Dupla Cables

Chris Wells wrote:

> Very good point since this is the whole point of the excersize.  We want
> a slow but steady exchange of water through the substrate. [snip]

This whole substrate heating cable discussion is getting ME heated up!
Skip ahead for those who've heard this before; this tirade is for the
benefit of the new folks spouting old nonsense. 

>;-[    (Fierce scowl combined with a quick wink)

The whole discussion seems predicated on the assumption that water
should for some unknown reason be circulated through the substrate. It
is also predicated on the assumption that heating cables are somehow
efficient at causing water to circulate in the substrate. Both of these
assumptions are unwarranted.

What happens it that through marketing propaganda, a myth starts to
evolve. Pretty soon folks start trying to copy or duplicate the
technology and the myth grows. Everybody just ASSUMES that those smart
folks at Dupla would never sell us a load of bunk (just to make
money)... Would they??

Here's what I think. If you add heat to a substrate (by burying a good
old fashioned aquarium heater or putting a reptile heater pad underneath
the aquarium), you cause the temperature of the substrate to increase.
This increases the rate of bacterial breakdown of organic debris in the
substrate thus releasing nutrients. It also increases the rate of other
chemical reactions, thus increasing the availability of trace nutrients
such as iron. This would only be beneficial if these nutrients were in
short supply. If the substrate is designed properly, iron and other
nutrients won't really be in short supply at all. Therefore substrate
heating is unnecessary. 

And by the way, it has nothing to do with circulating water through the
substrate or somehow banishing the evil gremlins of "anaerobicity".
Anaerobic simply means with out air or oxygen and is the normal
condition of substrates. Substrate reduction processes which liberate
iron and manganese and phosphates RELY upon the substrate being (to a
degree) anaerobic.

Oh yeah, I almost forgot. Happy New Year!   <;oP

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!