The Ebb & Gro 12-plant Hydro system is the most versatile ebb & flow system on the market. It is a simple system that uses 2 pumps and gravity to flood and drain the planters about 3 or 4 times per day. The fill drain cycles are controlled by the controller unit (the square white container) to control the feeding schedule that you set on it's built-in timer. This system can be set up in many different sizes and shapes to fit your exact growing needs. You can add up to 36 additional grow pots for a 48-Plant grow system.