Take a look at at the air bubbles produced by an aquarium aerator. Watch how quickly the bubbles rise to the surface. They provide little aeration, but are aesthetically pleasing to watch. Bubbles must remain contacting the water, if they are to do the job properly. A good rule of thumb is: The smaller the bubble, the longer it will remain suspended in water to dissolve.
The smaller the air bubble, the more slowly it will rise, giving it more time to dissolve in the water.
Due to the higher density of salt water, air bubbles are usually smaller in salt water than in fresh water.
A large 20mm bubble has a volume of 4.19 cm3, and a surface area of 12.6 cm2.
You could make 260 small 3mm bubbles from the large bubble. They would have a total surface area of 83.6 cm2. This is 6.6 times the surface of the 20mm bubble.
The small bubbles, can theoretically aerate 6.6 times as much water with the same amount of air.
Knowing the importance of air bubble size, the effectiveness of different aerator systems becomes readily apparent!