EHEIM Quick Vac Pro Automatic Gravel Cleaner and Sludge Extractor is a unit that no aquarium hobbyist should be without. It's fully submersible for complete aquarium cleaning or quick spot maintenance. Customers no longer have to deal with messy hoses and buckets. With this unit you can clean the floor of your aquarium easily between water changes. The power of the unit is designed so that dirt is taken up withoutåÊdisturbingåÊthe gravel and itsåÊpurifyingåÊbacteria. A filter compartment retains the dirt while letting the water flow immediately back into the aquarium. The filter is easy to snap off, wash, and reconnect. Batteries are included.