Deep water culture (DWC) is the one of the oldest method of hydroponics to date. In this system, the plants roots are submerged in water that is aerated typically by using an air pump and air stone. The advantage to this system is the simplicity of technology and high level of humidity in the root zone. The disadvantage of this type of system is that if the source of oxygen in nutrient solution is reduced or fails, there is limited capacity for the plants to maintain vigor. This method is extremely productive and popular for production of lettuce, herbs, and other leafy greens.
In this method of hydroponics, a thin film of nutrient solution is constantly flowing across the plant roots in a tray or trough. Like aeroponics, this system utilizes very little to zero growing media for plant roots to colonize which in the event of pump failure gives very little time before roots dry out and can lead to loss of crop. The advantage of a NFT system is the high level of oxygen in the root zone and the relative simplicity of the components using for fertigation. This system is most popular for growing leafy greens and herbs at the commercial production level.