Re: Plant Lighting Requirements

I've been very interested in following the lighting requirements 
thread.  By default (vegetative species demands aside), I would try 
to use the suggested 4 watts/gallon of light.  However, it seems only 
logical that this number should come down on larger systems.

To me, the reason is simple (I've been waiting to hear one of you
plant gurus mention it!  :-)  In short:  application efficiency.

Am I all wrong?  In an extreme example, a 100-watt MH over a 10
gallon aquarium will be applied more *inefficiently* than
the same lamp over a pond.  In theory, all light vectors will 
penetrate the pond to their maximum energy depth (or until they
hit bottom), while many of the light vectors will leave the 10 gallon
aquarium laterally (or possibly miss the aquarium entirely, if
the lamp is not low over the aquarium).

Thus, it seems to me that efficiency in application of light
over larger tanks simply make better use of non-vertically
emitted photons.  While these lateral photons are clearly not
as highly concentrated, my stated assumption is that their 
photosynthetic potential is significant.

charleyb at gr_hp.com
(or try) charley at agrostis_nrel.colostate.edu