My 220gallon reef had an overflow into a wet/dry filter (took up about 25-30 gallons of one end of the tank, behind a baffle). From there, it was into a sump, then 4 filter stages, before being returned to the opposite side via a pond pump. I loved the set-up, easy maintainance, and was an easy way to feed inverts (would put liquid food into the final stage filter/return hold, and it would distribute pretty evenly. Would also put brine shrimp I'd hatched in there, and watch the fish swim up into the chowline!