Aquarium vacuums, or hydro-vacuums, are used to clean the interior of aquariums during water changes. Over time, matter builds up inside from uneaten fish flakes, animal waste and other biological materials. It is important to remove this excess debris to reduce the risk of harmful bacteria and fungi.
Hydro-vacuums work by sucking up waste material from gravel. Some aquarium hobbyists believe that vacuuming the entire floor of the aquarium can have a harmful effect on beneficial bacteria. It is therefore recommended to vacuum only one side of the tank, alternating sides with every water change. Other considerations for aquarium care are just as important, such as regularly changing filters, adding fresh water weekly and monitoring temperature.