I have a Bak pak 2 on my 55g, I have a wood airstone with a strong air pump ( I don't know exact model ) and It pulls out alot of gunk, its important to clean the intake on the MJ 1200 regularly, I also filed the three slits in the intake piece to give more flow (the water flow part, not the air opening).
With the airstone mod I am very happy with the output.
I have a Remora C pro coming for my 37g which is going to be FOWLR, Im going to be intrested in the comparision to my modded bak pak2.