Sorry reefbound I forgot to say I have two slimline aqua light t-5's on the rear of my tank. I had these beforehand and just threw them on there with the new NOVA fixture. T-5 lighting offers more Lumen output then any other flo. lighting source. While the initial wattage is lower the output in spectrums is in fact higher. This means that with T-5 lighting you can have less wattage and still be getting better results because the spectrum is much better. This is a good thing in terms that T-5 will use less electrical power and still put out better spectrum. You can keep RBTA's, clams, even SPS
corals and more under t-5 lighting will exceptional results.
My girlfriend keeps a densly planted freshwater aquarium and she made the switch from Power compact to T-5. Her plants were doing way, way better under t-5 and after seeing these perform I was like Man I need some of those. That is why I changed from my old 400 watt fixture to the new 214 T-5 fixture. The fact is I am seeing the same results, maybe even better on some LPS
corals that I was seeing under 400 watts of light.
More important than wattage is spectrum, and making sure you mix white light with actinic and that the actinic comes on before and goes off after the white.
I am not slamming metal halides at all since I beleive for an all SPS
aquarium they are the only real choice if you want to achieve the glimmering effect and maximum growth. I however dont beleive that Halides are the most practical and best performing fixtures for reef aquariums, I think they are more suited to reef aquariums that specialize in SPS
corals. I think that T-5 and Power compact flo. lighting are far better in terms of heat output, and power consumption than any halide. Unless you are keeping only SPS
corals why pay more in electricty, more for bulbs, more to cool your tank, all so you can get a glimmer effect??
I still think that flourascent lighting (SO, T-5, Compact Flo. etc) is the king of lighting in any aquarium situation.