For a frag tank i would recommend strong water movement and more light spectrum around the 6500 and 10000k range, from what I have seen with past experience corals grow much faster under that lighting spectrum, but tend to not color up as nice... place them under a 14k bulb etc and you get better color with less growth.
Just my experience, but also keep in mind the corals you are trying to frag/farm has alot to do with it also.
John can probably provide more specifics.
brandon