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Re: More on Blue light

Hi, Ivo...

Unless I misunderstood, blue light (400 - 500 nm) is essential and used
by corals.  I have kept corals alive under just blue light for 5 months.
However, freshwater aquatic plants do not utilize it and will die. 
Micro algae in saltwater aquariums will die under just blue light.

Merrill Cohen

> > Not quite so. I converted the curves published at
> > http://www.aquabotanic.com/paper2-6.html from their standard 1m depth to a
> > "typical" aquarium depth of 16". For pure water, absorption at the blue end
> > (400-500 nm) is effectively zero. But for all other cases: pure water at the
> > red end (600-700 nm), and water with a reasonable amount of organics,
> > absorption is in the range 20-50%. Significant IMO. Of course, this should
> > affect mostly low lying plants. Stem plants and large swords for instance,
> > should see less of the effect.