Deep Water Culture (DWC)
Plant roots, like human beings, need air as much as water and food. Root rot plagues hydroponic growers who neglect to supply ample amounts of oxygen where it's needed most. The greater the amount of air delivered to roots sitting in water, the greater the plant's overall health and rate of growth; it's essential to provide enough air and almost impossible to overdo. Taking this adage to the extreme, growers who use the Deep Water Culture method pump air to the bottom of individual deep plant containers to permeate the dangling roots with oxygen.
Marijuana grown in DWC systems can yield as much as a pound per plant with proper lighting and ventilation. The key to this technique is a longer vegetative time to develop many branches, thus creating more bud sites. Aside from the obvious legal advantage to growing fewer plants, after the initial set-up it turns out to be less work for much higher yields than other traditional hydro techniques.
In addition, roots that grow vertically support and promote larger plants. When roots grow flat, as in many typical systems, the taproots can't extend properly, hence the plants underachieve. This is the reason that DWC growers use deep containers. Oxygen is the only limiting factor; a DWC container should be fizzing with tiny air bubbles throughout.
Five-gallon buckets are the standard for DWC-style growing, and dark-colored containers work best to avoid slimy roots caused by algae, which thrive on light.
If white or light-colored buckets are used, they must be light-proofed with duct tape or insulation. Advanced DWC practitioners use coolers or big plastic storage tubs for fantastic results. Either way, cut a hole just big enough in the lid of the container to fit a mesh grow cup holding the plant in its chosen medium (expanded clay grow rocks or coco fiber work great).