They are not particularly hard to keep but they need to be set up properly. Choice of fish is also important.
You need the proper substrate, water flow, and carbon dioxide. PC lights will work but you want to get a different spectrum of bulbs than is used on saltwater. Carbon dioxide addition can be a "complicated" thing or it can be pretty basic (2 liter bottle, yeast, sugar, sodium bicarb, water with air hose and air stone).
They are beautiful and rewarding when they work out