R/B leds miss what makes hps so good- the mid band
The following is copied from The Lurker (TL)
This is a Eye Hortilux HPS vs. Photosynthetic Absorption Spectra Curve.
I'm glad we've finally gotten some good studies on green light over the past several years, as has been mentioned previously (link) by a few of us.
While 'every lumen (or rather, PPFD) is sacred', I'm of the camp that would prefer a higher level of (adjustable) full-intensity, multi-spectrum (i.e. 'white') light incorporated into the main fixture, for that very reason.
And with the recent increases in the efficiency of neutral whites, there's no reason why you can't get perfectly good results with just a two-channel, adjustable led fixture (neutral white, and red), supplementing with the aforementioned only as needed.
(note: neutral white I called 'normal white' here for some reason. Wonder what I was smokin' at the time...<whistles>)
As one can see, the CREE Neutral White (I call it 'Goldilocks', because it's almost 'just right' ) has a RSPD that still allows nearly ~25% of its total power in the blue range (and plants only really 'need' ~8-10%), and more that 1/3 of which (i.e. the area under the curve) is over ~580nm or so (which has a Photosynthetic RS of over 90%!) - which is much better than even your typical 'Enhanced HPS'.
So like Gastanker, I too thing these whites are very SEXY