I use the T5 lighting and my coralline is growing great. Cost is about 60 bucks for your size tank (if buying Coralife- Aqualite- has actinic and 10K bulb in fixture. I use two for my 45 gallon that is 24 inches deep. Pleasantly surprised that I am able to shelter a carpet anemone that sits on the bottom as well as condy anemone, yellow polyps, pagoda coral, finger leather, trumpets, etc...most of these don't require high lighting except for the carpet). I do have a metal halide but I don't use it because there is no need - it evaporates the water very quickly, so I stick to the T5.