I have a 55g FO tank and have been uasing a skimmer. BIG difference in water quality and fish activity. Before the skimmer, they would just kinda chill and be a bit lethargic and the water wasn't particularly clear. Now they are all over the place and the water looks great. I would recommend one, but it also depends on your bio load/ feeding habits. You do what is best for you and you tank. If you do get one though, DO NOT get a seaclone. junk, junk,junk.