I designed this model in an effort to clean my sand substrate with a Python Water Changer without having to worry about sucking sand into my drain.  It can be printed without supports and pressure-fits onto the intake of the water changer.  The small opening increases suction power and the long tube allows to you reach more small spaces.  To clean your sand during water changes, hover the tip just above the top of the sand to pick up debris.  Your goal is not to purposely suck up any sand but when sand does get sucked in, it loses momentum and falls out of the higher pressure stream in the initial intake tube and falls into the trap at the top of the print.  To release the sand, simply remove the print and tip the sand back into your tank.