Well, as im sure you've heard before, you should wait until your tank is really established and mature to add certain corals if not all. All i know is that corals like anemone and softies should be held off until the tank is matured. Which is like 8months+ I dont really know about other corals. The only thing worse than dead fish, is buying a 50$+ coral and then having it die. That would be bad. Also, what kind of lighting do you have in your biocube? You know your going to need something like T5 HO
lighting if you want to have a wide range of corals to choose from in the future.