okay so let me see if I understand this right.

In the main res (the big one) you have a drip column attached to the intake (which is coming from the individual WF units) and on top it is attached to an air pump which pushes the intake water out to either each individual WF or into the controler (this is the part which confuses me).

So then in each individual WF unit, you have a second drip column inserted but instead of attaching a ring you attach a line which goes back to the main res (which is what i referred to as the "intake" before)