Deep Water Culture (DWC) is a hydroponic gardening method in which plants are grown directly into a large pool of nutrient solution. Typically, plants are placed in net baskets full of a growing medium such as perilite or expanded clay pellets. These baskets are then placed in a reservoir (5 gallon hardware store buckets are a popular choice among hobbyists) to submerge the plant roots. The root mass will continue to grow down into the reservoir, slowly filling it with loosely packed roots. DWC systems require a well oxygenated nutrient solution to keep the roots from drowning and rotting – an air stone and a bubbler are often used to sustain adequate dissolved oxygen levels. As plants consume water, the reservoir level will recede, exposing the roots to even more oxygen and promoting prolific growth. The downside of frequently changing water levels is that pH and EC levels tend to fluctuate, especially in smaller systems. Maintaining a large number of small reservoirs, such as 5 gallon buckets, can also become tedious. To combat this, recirculating designs are implemented to tie together smaller reservoirs into one large system, which will tend to be much more stable and require less work. Read more »

Continuous Flow or Nutrient Film Technique (NFT) hydroponic systems use a shallow stream (or film) of water recirculating through a channel to deliver nutrients directly to the plant roots. The stream is shallow enough that the uppermost roots laying in the channel are exposed to air, providing the plant with access to lots of oxygen in addition to all the water it needs. To control the depth of the water stream, NTF systems use channels sloped at 1:30 or 1:40 (around 1.5 degrees). For most plants, the optimal flow rate in each channel is 1-2 L/m, and a maximum length of 10-15 meters is recommended to avoid nutrient depletion at the end of the channel. Because NFT style systems rely on a pump for nutrient and water delivery, there is no protection against power outage or system malfunctions. Plants will quickly die if the pump stops running for more than a few hours. NFT systems are best suited for leafy plants, due to the restricted channels which would not be adequate for the massive root structures necessary for most fruiting plants. Read more »