Air Pumps An air pump can provide mainly two things: 1. Increase surface area 2. Improve circulation Gas exchange - where the water dissolves oxygen and other gases from the air and releases excess carbon dioxide and other gases to the air - occurs over any and all surface area where the water has contact with air. By increasing the surface area of the water, each bubble gives the water further opportunity to release carbon dioxide and take up oxygen. However, this improvement from an air pump is shadowed by the improvement in circulation that the air pump can effect. The improved circulation will move highly oxygenated water from the surface lower in the tank allowing water with more carbon dioxide and less oxygen to the surface of the tank where id can release its carbon dioxide and take up oxygen. We deal in air pumps starting from 3 watts to 138 watts catering to all different sizes of ponds and aquariums.