i am running the MR-2R. I was running a BL-55 on it for several months. Was never happy with it. It skimmed ok, but if i fed the fish, changed filter socks, it would take a day minimum for it to build up another head of foam. It would just run flat forever. The bubbles were just to big to do anything. I had access to a BL-70 so i put that on there to see if it would help. WHAT A DIFFERENCE! It made the same kind of bubbles that you see the NW skimmers making. It never came close to that with the 55 on it. Problem was that the pump surged because i couldnt run the water level high enough. It would overflow instantly. Got the 12" extension, raised the becketts 8" and this thing is a monster. This is the way it should run IMO. 30 minutes after feeding and its back to skimming. The pictures were taken right after i hooked it up so no nastiness in the cup yet.