I think a refugium is vital to a larger tank. The smaller nano tanks I think can run quite well with frequent water changes and no fuge. But I would never run a larger tank (55 gallon and up) without one. I love how diverse my fuge is with life. It provides constant live food for my fish like pods and mysis shrimp. And the chaeto grows super fast. I harvested more than half of it just a couple weeks ago and gave all of that away. It has already almost doubled in volume. I spend just as much time watching the critters in my fuge as I do the critters in my display.