Hydroponic set up - pvc pipes. We made two of these--one 4" and one 2". Very successful. Nice job!
The basic configuration includes three bottles that act as plant holders, a bottom reservoir to capture/hold water, and tubing to move water through the system. It also utilizes a small air pump that uses water displacement to elevate the water up to the top of the system, where it can then trickle down through each plant.