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"Richard J. Sexton" wrote:
>You'd think that any plant that performed better under gro
>lux than sublight would be at an evolutionary disadvantage
>to the latter. Who knows.
I'm no expert in plant biology, but I think this point is very strong
in making the case in favor of full spectrum (aka sun light...) ligthing.
The grolux spectrum was designed to mimic an average photosynthesis action
spectrum, but plants use other pigments as well. The absorbancy spectra of
say, phycoerythrin and phycocyanin are totally different from the
photosynthesis action spectrum. They peak in the region 500 - 600 nm, almost
exactly where photosynthesis is at its worst. Only a full spectrum light
would be able to fill in all required wavelength regions with a balanced
number of photons.
The argument that plants adapt to almost any kind of light is certainly
true, but IMHO there is a cost in such adaptations. I imagine that, fed with
light with a very different spectrum than the sun's, a plant would have to
make up for the lacking photons by switching to alternative metabolic
mechanisms, which would most likely be less effective than the "natural" one.
These alternate mechanisms could work given the very unnatural conditions in
which plants are usually kept in aquariums. Success would only be achievable
by chance though, given that there is no comprehensive theory to serve as
a guide. On the other hand, adhering to full spectrum ligthing would ensure
that at least this element is in accordance with nature's "best" way of doing
That said, I'm a fan of grolux-type lights, since they are so effective
in enhacing fish's reds and blues. I still believe that a mix of grolux
or equivalent (Triton, AquaGlo, Perfecto) with full spectrum high CRI
bulbs is the best way to illuminate a planted aquarium, provided the
intensity requirements are met as well.