The Reef Octopus VarioS 4 Controllable Circulation Pump is a safe and efficient controllable pump with integrated memory, two different pause/feed modes, and silent operation.  This pump has five flow settings.  It can be can be connected to a 3rd party controller such as an Apex.

Aquarium water pumps are a necessity as they provide a current for your aquarium, and move the water through your filtration.  There are various sizes depending on your specific needs.  If there is not enough water flow, your aquarium will be more susceptible to algae growth.  There are multiple types of water pumps.  Some internal, some external, and some with the sole purpose of wave making.