Very nice project. I was working on something similar and would love to see your progress.
I just wanted to make a suggestion. One of the main stress factors for fish and corals is instant light switching. How do you control your light-cycle? Simple timers?
Instant turning on and off of lights? This might be scaring the sh$& out of them and might reduce their life.
Now as I have seen, you are using Metal Halide lamps, which I don t know if they are dimmable.
My project used a dimmable ballast for fluorescent lamps and simulated dusk and dawn. You can use something like that to bring the light up initially, and then when it is on its peak, fire up the metal halides. The reverse at night for killing the lights.
The results from this was that my fish where far more social and active, even with people on the front glass.
Plus the aquarium looks soooooo cool when the device is simulating dusk/dawn. I can t even imaging how cool a reef would look with two dimmed actinic and daylight tubes.