It really depends. You don't *need* metal halide lighting if you only want to keep a variety of certain soft corals and LPS (Large Polyp Stony) corals. I have five corals under Power Compact lighting, and they are doing very well!
It's really necessary to research the individual coral, finding out what lighting/water flow/additives it needs.
I think the worst mistake, with regards to keeping corals, is the impulse buy!! It pays to know what, exactly, you're bringing home....
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~Drew
10G Nano * 10G Sump * Deltec MCE 600 Skimmer * JBL Viper 150w MH * Zeovit * Vortech MP40W
Millions long for immortality who do not know what to do with themselves on a rainy Sunday afternoon. ~S. Ertz
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