text: Actually, any aquarium pump will work.  To make smaller bubbles, the air should pass through a diffusing element or stone.  This will have small pores and a relatively large surface are to release the air pressure slowly over a larger area.  This results in smaller bubbles. These are available for purchase at a store that sells the aquarium pumps.\n\nYou could also probably make one by plugging the end of the regular aquarium pump hose, and perforating it as much as you need with a needle.  Some testing is required, but you should be able to find the right hole (needle) size, and the number of holes to meet your need.