Active Aqua Grow Flow 2 gal System w/Controller Unit & 1/2" TubingActive Aquas Grow Flow is the most efficient ebb & flow system on the market. With the Grow Flows easy to program controller unit, you can pretty much "set it and forget it." And since your pumps are only pumping a short time each day, the system is extremely reliable and efficient. Just set the fill and drain cycles, and the controller unit does the rest! As for safety, the Grow Flow is the only unit available with fail safe overflow protection. If