I recently added metal halide to my nanocube 12g. I will never go back to PC. My corals are growing great already and the look is just fantastic. Granted, my old bulbs were too old so that doesnt really give a fair comparison. From an economic standpoint PC bulbs need to be replaced every 6 months. If you have alot of PC bulbs in the hood that can get VERY expensive and still not be as good lighting wise as MH. Metal halide bulbs can go about a year (depends on color spectrum) and you only buy one. either option will probably work, but just wanted to share how happy I am with MH. Plus you are limitless at what you can keep in the tank with the superior lighting.