Metal Halide Questions VS. T5

[kien]

As fishy said, the 8bulb T5 on an 18" high tank will be more than enough to grow pretty much anything. The halide option is OK too if you can look past the heat issue. Another thing to consider is the fact that the halides will shimmer your tank, where as the T5s will not. To get shimmer while using T5's you'd have to supplement with LEDs.

I personally prefer a combination of T5s with Halides. Halides to grow corals and for the shimmer effect, and t5s for supplementation and colour adjustment.