Yeah, I was tempted by the CFS700 but when I noted the dimensions included a height of 27 inches with nozzles, I realized it would never fit under the tank or inside the stand. Too bad they just did not make a CFS700 that was bigger around like the FX5 not taller, but I think that whoever makes the CFS500 is also contracted to make the FX5 as many of there parts are interchangeable. The big difference being that Fluval as the client-manufacturer obviously requires thicker and better quality plastics.