Mine is a little different.
Not put together or in use at this time, but, i use a 60 gallon aquarium pump with a five gallon cooler.
Inside of the cooler i have three air lines. Two go in one direction and the other goes in the opposite.
No, i know those of you who have more experiance may have some constructive critcism, but i will say i have used this in this way off and on for years, and my beans, tamatoes and begonias love it, it works.
Perhapps not as well, but it was inexpensive to make.
I think i spent $20 on the whole thing...