i have one on my 120 with my fx 5. its a good filter but i wouldn't use it with a big bio load alone. it would work on 120/150 by itself if ur keeping a bunch of tetras,minnows or smaller low waste producing fish. it has a good sprayer bar for surface agitation as well. but for tanks 0-75 g its pretty damn good. there's lots of other filters out there to keep in mind of.