If I remember my biology correctly, don't red plants use a chemical other
than chlorophyll to absorb light, hence the different color. And apparently
this other chemical is less efficient, meaning you need more light to
produce the same amount of food/energy/etc. So if my memory serves me
right, this would explain why people would think that red plants need more
light, which they do if they have to produce the same amount of
food/energy/etc., but maybe they don't need to produce the same amount,
maybe they are fine with less.

Harry

This is certainly true also as a reason ro part of the story. Some red
plants grow at break neck speeds. Light transfer is mighty efficent
and extremely fast also. Beta carotene is the main pigment. This is
different and serves a different function than anthocyanin, but
neither colored pigment possess Nitrogen wereas Chlorophyll is rich in
it.

The main point about the plant being "fine with less" is also very
true.

I had a list on the APD I posted some years back about the differences
between a shade plant and sun plant which might be applicable here as
well.

http://fins.actwin.com/aquatic-plant.../msg00293.html

Regards,
Tom Barr