An airstone (a way of diffusing and spreading tiny o2 bubbles) is connected to an air pump which pumps o2 through the airstone. The stone is under the water the pump above. O2 to your roots is a great thing.
As far as doing a stock aerogarden grow goes i have not done it so i cant really say, but i would recommend to get some other nutes and extra lights.
Thats all i done and got good enough results for me.