This may be a stupid question. I have a Kracor 15 gal holding tank. I am replacing the head and all the lines. The tank has both lines, the line from the head and the line to the pumpout port on the top edge. Coming out of the top left side of the tank is a 90 degree PVC elbow. The tank is mounted on the port side, under the V-berth. So here is the stupid question? How does pumpout work if the line to the deck top comes out of the top of the tank? If must work, since the tank was dry when I bought the boat. I know the boat was set up for direct overboard dumping, and this was disconnected a few years ago by the PO. I just don't understand how this works. I haven't opened the tank to look inside, but shining a bright light through the side of the tank, I can't see where there is any type of line or pipe leading from the top of the opening to the bottom of the tank.