Pickup tube whadya mean pickup tube?!?! Not familiar with the tank setup on argos, but I don't recall ever reading anything about a pick up tube. Is that for real, they aren't gravity fed through the bottom of the tank? If so that could explain a lot, if it has one, then you probably hit the nail dead center! You could blow the tank up like a balloon and never get a drop out if this is the case! And there is a better than good chance it could be knocked off during the draining/cleaning/drying process!
DESTRUCTION is just a couple of vowels down the street from DISTRACTION