thats a 5.5 gallon if my memory is right(dont much like math :P) thats what i started out with and for awhile did just fine. i used an hob for the filtration and a little powerhead too. i had about 7 lbs of live rock and i was able to keep some zoos and small leathers just fine in it. just remember to keep a very very close eye on ur salinity. i had to add water about twice a day just so it wouldnt get out of whack too fast.

hope it helps, steve