Hey buddy. Pop 22 did the research and initially posted, but i followed along and tried one myself. It is a dwc that solely relies on air breathed in by plant itself with no aid from some pumping system. It just sits in a pail of water and nutrients with a one inch gap between the bottom of netpot and nutrient solution. That gap provides the air it needs. If you google kratky you get the doc that created the method and his research.