The Ebb & Gro (from 12 to 48+ plants) is the most versatile ebb & flow system on the market. With many growers going from large numbers of small plants to fewer, larger ones, the Ebb & Gro fits the bill! 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 its built-in timer. This system can be set up in many different sizes and shapes to fit your exact growing needs. You can expand your system simply by adding more grow pots. The system works by connecting all of the grow pots to the controller unit. All necessary tubing is included with the system, just add grow rocks. Just set the timer to fill and drain the pots about 3 or 4 times a day. When the fill and drain cycle that you set comes on, it turns on the pump in the large reservoir (the 55 gallon blue drum), and starts filling the controller unit. Since the grow pots are all plumbed to the controller unit, the water in the entire system starts to level off with the controller unit. When the pots are full, and your drain cycle starts, the pump in the controller unit pumps all of the water back into the reservoir. When the level of the water in the controller unit goes down, all of the grow pots levels go down also. Then the controller unit waits for the next fill and drain cycle a few hours later. The grow pots are 2 gallons and are filled with grow rocks. Each grow pot consists of 2 pots nested inside each other, the inner pot has a lot of holes in the bottom to allow the water to enter the grow rocks and the root zone. This will allow you to be able to pick up the inner pot and move the plants from one site to another on the system. This will allow for level plant growth, even at the edges of your garden where the plants don't get as much light! Since your pumps are only pumping a short time each day, the system is extremely reliable. Your plants have 2 gallons of space in which to have root growth, so the size of your plants is not an issue. If they get larger than you anticipated, you can space the grow pots further apart. The the plants can be as close as 10" apart, so they can be packed into a small area if you desire. Versatility is what you get with this system. Additional grow pots can be added at a later time. Each 6 pot add-on includes all of the tubing and fittings needed, but you will need one 50 liter bag of grow rocks. The Controller unit (with pump) is available separately if you wish to make your own system.