not the same as the airstone totally because these bubble are more intense than the air stone. i have been building my own and it is not as easy as in my head, I'm on my second prototype now, the first one did not put enough oxygen through the soil and the seeds and keeping the soil at the correct temperature in my cold basement. ill keep working and let you know what i find out...
basically from what i can tell it is a 7.8L 2 port air pump a 4 quart or less grow container. from the bottom up is grow stones, then a layer of fiberfil (polyester) to prevent the soil from clogging the the air hoses, then the soil. water it until is is completely saturated and the air pump bubbles the soil. i don't really know if the bacteria are going to thrive in such a moist environment but I'm not sure we will see!