Hi! We started a 55g tank late in 2010 and have had great success so far. Out of our 12 started fish, only 1 has ever died and we are pretty sure he was messed up when we bought him. He never ate very much. We currently have 3 parrot cichlids (our babies!), 4 black skirt tetras, 2 x-ray tetras, and 5 cherry barbs.
We have done regular water changes (almost always never more than 1 week between them) of 25% or so of the total water. However, I have never opened up the Fluval and cleaned or replaced any of the media.