Air pumps (also called diaphragm pumps) move air into the aquarium or pond. Air bubbles leave the air stones and enter the water, thus increasing the oxygen content. This oxygen increase partly comes from the small bubbles dissolving oxygen into the water on their way to the surface, but mainly from air bubbles moving the water surface as they rise, thus increasing the surface area. A larger water surface increases the exchange of gas and thus enables the aquarium water to absorb more oxygen from the air.
If you’d like to buy a JBL PROSILENT diaphragm pump or are looking for additional information: Air pumps
Find out more about the technical options for aerating an aquarium here: Air pumps