I agree with your earlier statement about using different LEDs to 'round out' the available spectrums. If you look at the spectrograph of the white LED; you see that it puts out more light over a wider useful spectrum than the Halide. If you use colored LEDs, their outputs are extremely (unnaturally) narrow in bandwidth. As it was pointed out earlier; some types of chlorophyll fluoresce at different frequencies. Unless you know which corals have said pigments and seek out very specific bins of diodes; you may or may not "hit" them and end up delivering an endless supply of food for one of the hundreds of species of nasty pest algae in your tank that DOES have it.. The fluorescent chlorophylls are secondary. They just convert unusable wavelengths of light (by fluorescing them) to useful wavelengths for metabolizing. Your Chlorophyll A responds to light in the near-UV spectrum, while B likes blue around 450nm. Importantly, human eyes also respond to these frequencies in odd ways. It makes our critters happy and looks really neat to us. If you use wider spectrum (white diodes of different bins) to fill in the other wavelengths; you hit all the sweet spots.
As far as bigger diodes; the first reason I use them is that most of them are usefully driven to 12VDC. How many big, cheap, reliable power supplies can you think of that put out primarily 12VDC? Most of them. Big PC power supplies can put out over 24 amps of it. Automotive battery chargers can put out 200 amps of it easily. Almost all electronic devices are powered by DC and have a power supply to rectify it. I run a max of 120 watts at 12VDC. The only power supply I use is a big, quality PC (I'm talking computer) power supply and it has its' own cooling fan and owner serviceable circuit protection. I don't like the idea of using a brick encased in plastic without active cooling to supply that much current. The folks at Meanwell are making a killing convincing people that disaster will strike if their drivers are not used. Everyone comments about the "runaway current" that can occur with improperly driven LEDs. Well, if you wire 12V LEDs in parallel to a 12VDC power supply; you will never exceed their current rating. If one burns out, voltage never appreciably changes. I also challenge Meanwell to match the surge and ripple characteristics of a computer power supply. Look at the output of even a bargain basement PC supply on an oscilloscope and it's almost indiscernible from pure DC. You have to buy 1/3 the diodes, 1/3 the optics, solder 1/3 as many connections, etc. for the same light output. The dimmers are cheap as well, and some are even PLC compatible, of which I have five:
one for the cooling fans (also 12VDC computer items)
one for blues
one for the 100w white LED (6000K)
and one each for the reds and greens (which are not used anymore)
As far as manufacturers; I'd look at Edistar and Epileds. They both make good usable diodes for reefing and have good product documentation. Especially Epileds, In my opinion. Gotta go; have new LR and critters to acclimate!
