This extremely reliable system has proven itself over the last 25 years! Grow one large plant or up to five small ones. It increases oxygen to the roots for vigorous growth and healthier plants. The WaterFarm� comes in two forms, complete and modular. The complete WaterFarm� is designed to be a stand-alone system and includes 4 gallon reservoir, 2 gallon growing chamber, pumping column, column support tube, drip ring, 1/2 in grommet, drain level tube, Elite 800 air pump, 9L clay pebbles and 3-part Flora Kit. The modular unit comes without a drain level tube, Elite air pump, clay pebbles or Flora kit, as it is designed to use with a General Hydroponics� controller supplying multiple WaterFarm� units.