TDB, your tank is absolutely breathtaking! Do you have a build thread anywhere? I'd be curious to read a bit more about the other equipment you use, husbandry, where you keep your water chemistry, etc.
As for the topic at hand, my tank is only a couple months old, so I don't have anything in the way of SPS, but I am planning to in the near future after I finish getting everything dialed in and stable, and once my refugium is up and running (waiting Dow 795 to cure now, should be another week or two).
On my tank, I'm running buildmyled.com LED strips as what amounts to a "mid-day" lighting source. They are 48", 76W strips using Phillips LEDs, each strip having twenty four 6500k whites, four 400nm UVs, sixteen 450nm royal blues, eight 470nm blues, four 525 greens, and four 660 deep reds. They are extremely bright, and have an appearance similar to a "10k" MH bulb. I have also added a 4x54W ATI Sunpower fixture, as after some reading I am of the opinion that LED + T5 is the best combination for me personally. I get the very full spectrum (including lots of light throughout the 410-440 range, where my LEDs were a bit underpowered), very wide spread, and a better dawn/dusk effect.
I tend to think that some of the issues people have with LEDs are tied to a relatively small amount of light in the violet to indigo range, as there are just not that many LED chips that pack much punch in those wavelengths. I think another issue is that LED light is very direct and focussed compared to T5, or even MH. It seems that light does not enter the tank at quite as many different angles, which I think tends to lead to some parts of a given coral receiving dramatically more light than others over the course of the day. Some light will always be reflected from sand, glass, and rock, but I don't think the light hitting many colonies is as evenly distributed with LEDs, especially with the relatively small number many people run over their tanks.
A lot of people buy a small number of very intense (and very expensive) LED fixtures, because they "look" bright enough, and often can't be run at 100% for more than a couple hours without toasting a lot of corals. My thinking is that TBD's approach results in much more even distribution of light, so that more parts of his colonies are getting the right amount of light, which leads to more consistent and intense pigmentation.
I know its off topic, but would mind telling us what you fed your yellow tang to get it to morph into that lovely shade of orange?
