I have a long clear tube (Siphon?) that I'm guessing is a gravel vac. Thats all there is to a gravel vac, right? So how do I siphon water and suck up poop with it? I've heard you just suck on one end (WHICH end? Thats what I can't figure out. One end is the end of the tube and the other is like a plastic thingy on the end... not sure how to describe it) and that will start the water coming out. I tried sucking on both ends but I guess I'm doing it wrong or not sucking long enough?