Lets bring this thread back from the dead because my durso has become very loud lately. Nothing has changed in my plumbing at all. Today I tried to drill a bigger hole in the cap, but that didn't do much. Maybe tomorrow I will give my return pump a bath in vinegar, maybe it isn't pushing out enough water to keep up with the durso. Since the tank is in my living room, my wife is going to kill me if I can't get this quiet soon.