Tom,
I have a 215 gal tank (72" x 24" deep x 28" tall). I have 3 reef tech LED fixtures (180 watts each). Each fixture uses 24 3 watt Cree XPG white (7K), 24 3 watt Cree XPE Royal Blue 450nm and 12 3 watt Cree XPE Blue 465 to 485nm LEDs. I have been using these lights exclusively on my tank since Nov 2011. I started adding coral frags on or about 03/12. Using LEDs has been a learning process. Without the benefit of a PAR meter I started low in intensity (30% white, 60% blue & royal blue). I slowly increased this until I fried half my corals......50% white, blue and rb approx 75%...then reduced again. I currently stand at 40% white, 75% royal blue and 65% blue. I am totally not satisfied with growth or lack thereof, (I haven't gotten to the point of heavy concern regarding coral coloration). After 1 year only certain corals have shown visible growth yet still not outstanding growth while other corals either perished or show no growth whatsoever (although they remain alive). Now there are of course other factors to consider. My fixtures are approximately 8 inches from the water surface. For flow I have 2 Tunze 6105's and a Dart return pump. I use a knopf calc reactor (the larger of the 2 models offered) and have an orca 200 skimmer. I am in the process of doubling the internal flow......I am also going to add supplemental LED lighting by way of two 1500mm x 75mm x 60mm (approx 60" x 3" h x 2.5"w) LED fixtures that each have 36 3 watt LEDs made up of the following color spectrums: 21 violet (400 to 420nm), 9 cyan (500nm) and 6 red (660nm) set at my specific array. These units/fixtures have manual dimmers for each color. I am hoping that by increasing the color spectrum and flow simultaneously that this will effectuate a major change. Time will tell....
Frank