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Re: Aquatic Plants Digest V3 #596

> From: "David W. Webb" <dwebb at ti_com>
> Subject: Re:Do substrate heating coils fertilize the substrate?

> Transpiration occurs, carrying water and nutrients from the roots to the
> leaves.
> 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.

David, An interesting hypothesis, and IMHO a bit of fresh air in this
otherwise gruelingly old topic! One practical note: If this is true, then
one should be able to get identical results with both cables and flat
heating sources such as heating pads, ballasts mounted underneath the
tank, etc.

And speaking of gruelingly old topics...

> From: rlind at nettally_com (Lindstrom, Rick)

> 1) Lighting?? I haven't seen the use of halogen lighting addressed. A visit
> to Home Depot revealed that one can buy a low voltage halogen lighting
> setup that could be adapted for aquarium use (lawn lights) relatively
> cheaply.

Halogen isn't discussed a lot because it's bad.  It's a FAQ.
From the Plant FAQ Q&A section (http://faq.thekrib.com/plant-qa.html): 

>>>
``Can I use those cheap Halogen bulbs from the hardware store?''

Do not confuse MH with the tungsten halogen lights sold in hardware stores
as utility floods or living room fixtures; Halogen lights are basically
high-wattage incandescent lights, and generate an enormous amount of heat
and are very inefficient in their light output. Some also find the
spectrum too yellowish. 
<<<

I would add, though, that if you're not trying to grow plants, having tiny
little halogen pendants can be quite decorative.  Soon, I think it may be
a moot point: I have a local friend here in lighting who tells me that
small 70W and 100W metal halide bulbs are available that may do the same
job but with the efficiency we've all grown to know and love.

   - Erik