Lees new Ultra Gravel Vac Self-Start Siphon feature has made aquarium maintenance a whole lot easier! With the Gravel Vacuum cylinder submerged in the water, simply move it up and down a few times to activate the Self-Start Siphon. Separates and removes debris from aquarium Drains and fills for routine water changes Self-starting siphon Gravel Vacuum Cleaners are designed to separate and remove debris from the aquarium during routine water changes. Can be used with and without wide-mouth nozzle and features a Self-Start siphon.