Hmm no perfect answer here. The subject has 2 dimensions..
IF you want just the fluorescence then you need an "invisible" light...
Keep in mind that some fluorescence won't be visible (or produced)
at different wavelengths..
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Note all the different emission colors and different absorption wavelenths.
Secondly you have the reflected back color (un-converted) which adds or subtracts the orig color and intensity..
A "problem" all on it's own.
See how the choice of excitation wavelength and barrier filter affects the appearance of coral fluorescence.
www.nightsea.com
From the chart and trying to get a "bunch" of pigments (of course you need them to begin with, another story) to fluoresce a best guess is to include 385, 410, 440 nm diodes going up to 490..
how many is even trickier since you don't want too much of the diode reflecting back at you and messing w/ the fluorescence..
Think you would need a lot of trial and error here but start w/ less of the more visible diodes than the less visible diodes..
Then again you need enough to span the tank..
Biggest problem is w/ the 440 and 490-ish diodes. esp 490 since it is readily visible to the human eye.
you might want to consider a "regular blue" in that case.. or plan on adding a dimmable cyan channel..
Well technically to get crazy each color should have it's own channel..
To be honest, since you don't really want to encourage too much photosynthesis you should do that anyways..
Easiest thing would be just a few 390-ish, 410-ish, for the majority and a few 440's..but overall as few as you can get away with.
If you use them as part of your daily "PAR" cycle it gets easier..but if like a night light, more difficult (enough diodes to cover the spread but not too much overall output).
Not really an answer though..sorry.
Oh , you can sort of model it off Orpheks..but better..
At least add a dimmable driver..Using LDD's and a hacked manual PWM dimmer is relatively cheap.
36 3W diodes run at about 2W for a 4ft bar. Density and more specifically output may be too high for long term use (many hours/day) though tank size dependent.
UV/Violet (380- 440nm) for maximum coral growth & color and fluorescence.
Just for reference.. but consider a "compromise" between the blue plus and the uv w/ added true uv of 385-ish and some reg blue or cyan.
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