The Ebb and Flow system is one of the most popular hydroponic methods for its simplicity and ease of use. It basically works like this: A reservoir containing nutient solution is located below a growing tray. The tray contains the plants that are in containers with growing medium (rockwool, grow rocks).The growing bed is flooded periodically by a small pump on a timer to feed and water the plants. The timer then shuts the pump off and the nutrient solution drains freely back into the reservoir drawing oxygen into the root zone. Ebb and Flow systems' are favored because of thier low maintenance, high productivity, and ease of use. Ideal not only for the beginner, but for the advanced gardener as well.