Water Tank Sight Tube added to allow quick monitoring of water level in tank inside port storage enclosure. Black label tape on the tube clamps mark 1/2 and Full Levels. One end of the tube tees into the 1/2 inch tube exiting the bottom of the tank and the other end tees back into the vent tube exiting the top of the tank. I got the idea of a colored ball or float from Sea Wolf (thanks, Joe).