The pump in the aquarium generates flow and enriches the water with oxygen. The pump is already included in standard water filters. It draws the water into the filter where it passes through the filter and then returns it back to the tank. Aquarium pumps are available individually with an internal filter or with external filter.

The pump is part of the filter system. It sucks the water into the filter, where it is cleaned using filter media and the bacteria that settle on it. After the water has passed through all filter materials, it flows purified through the outlet back into the tank. An internal filter includes the aquarium pump, the head with suction opening, housing and foam cartridges or other filter material. While the internal filter purifies the water inside the tank, the pump in the external filter pumps the water into the filter via a suction pipe and returns it back to the tank via a vent after cleaning. Most pumps can be individually adjusted with regard to the flow direction and delivery rate of the water, so that you can adapt these criteria to the needs of the residents of the aquariums. When using an internal filter, you should remember that the filter takes up space in the tank and reduces the water volume. External filters are normally used in aquariums with a capacity of 100 litres or more and have several filter chambers that you can fill with different filter media. In addition to purifying the water, the aquarium pump also has a positive effect: more oxygen enters the tank through the water circulation. Many water creatures enjoy living in the flow. There are special flow pumps for this purpose, which move the water more strongly.

Separate aquarium pumps can usually be attached to the glass panel with suction cups. 

If necessary, you should briefly rinse the inner filters of the filter system (if too much waste impedes the flow) with aquarium water. Rinse only the coarse impurities to get as much filter bacteria as possible. With external filters, you should only intervene if the performance drops noticeably. Rinse only part of the filter media quickly with aquarium water and only remove coarse dirt. Even if filter media must be replaced, never replace all at the same time.