Hydrofarm CAEBB12 Ebb and Gro 12-Site Hydroponic Complete Germination System The CAEBB-12 system increases the oxygen levels around the roots by repeated flood & drain cycles Each EBB-CTR controller can control from 6 up to 48 plant sites; plenty of room for expansion Reservoir does not have to be lower than the plants The EBB-CTR controller is all you need to control all pumping and level control functions This is an "Active" hydroponics system and the main advantage is that the Ebb & Gro system has is its amazing root and plant growth Not sold in OR