Lee's Self-Start Siphon feature has made aquarium maintenance a whole lot easier. With the Gravel Vacuum cylinder submerged, simply move it up and down a few times to activate the Self-Start Siphon. Gravel Vacuum Cleaners are designed to separate and remove debris from the aquarium during routine water changes. The Large Gravel Vacuum Cleaner features a 2” diameter x 16” long cylinder with a 72” long hose. It is ideal for use in hexagon aquariums and taller aquariums. The Large Gravel Vacuum Cleaner comes standard with the Wide-Mouth Nozzle. The Wide-Mouth Nozzle increases your surface coverage by about 20%, allowing you to clean more gravel surface without draining too much water.