You are asking if you can keep corals with live rock, sand, and a HOB
filter? Keeping corals is mostly about lighting and proper tank maintenence. If I have to break my sump down I will run a HOB
filter on my reef tank and there aren't any problems, but I have a nice regiment for tank maintenence and have exceptional lighting. What kind of lighting do you have and what kind of corals are you looking to keep?