I just picked up a used Pro3. THis this is as big as a small shop vac! Nevertheless, here goes.
1) The wheels should not be in the back, but in the front. If the filter is being used, once you disconnect the hoses, you'll wnat to lean it forward and out of the cabinet or from its location.
2) The Priming Pump is inadequate. It should be a lever, not a knob. I've worked on generators that require pumping, all have a lever. Even a small one will do. These is no speing needed on a lever.
3) This animal is dead silent! End of story. I thought it was off!
4) As a consequence of the weak pump, I filled up manually. With all the media, and I have extra pads, it drank up close to 4 gallons! That increases you tank capacity a bit! This is going to my 47G planted. Great, I appreciate that.
Ill add more as I go along.