I know I am late to comment, but as the other posters said the orbit is not a good choice if you want corals. I wrote up a nicve review on my thread the other day on it.
I have it over a shallow 40b tank and it cannot grow sps
is just about the limit for it. My nem is reaching for the light as well, def not enough for him. Over a 75g it would be almost useless. :-(
The tao unit mentioned early on is a great choice as it dims and will keep anything you want to keep as far as lighting goes.