For what size tank? One came with my 50 gallon cube and it was cool until I had any more than 4 or 5 fish in the tank. My bio load became to high.. But then again I tend to over feed. I ended up getting the SCA 303 and it solved my problems. Had to replace the impeller on the atman pump once as well.. Ten bucks, no big deal for the price of the skimmer