Im not sure what that tube does, exactly. I think it creates some type of airlock. One of mine came off, and I just epoxied it back on. While it was off, it didnt seem to run any different, though. If it is lost, you should be able to go to a parts store and buy a new piece of tubing to replace it. As a side note, please try to watch your typing. It was hard to follow the question you were asking.