Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

allow for daily evaporation. Replenish reservoir daily if necessary. Do not let nutrient solution stand in the table for more than a half hour. Submerged roots drown in the depleted oxygen environment.
    Flood the table when the medium is about half-full of moisture. Remember, rockwool holds a lot of moisture. Irrigation regimens will need to change substantially when temperatures cool and light is lacking.
    Ebb and flow tables or growing beds are designed to let excess water flow freely away from the growing medium and roots. When flooded with an inch (3 cm) or more of nutrient solution, the growing medium wicks up the solution into the freshly aerated medium.
Air Table
    Air tables are simple, easy-to-use hydroponic gardens. Seasoned growers and novices love their simplicity and low maintenance. The unique operating principle is simple, effective, and nearly failsafe. The nutrient solution is forced up to the growing bed with air pressure generated by an external air pump. The pump can run on ordinary household electrical current or a solar-powered 12-volt system. Once flooded, the nutrient solution stays in the growing bed for a few minutes before it drains back to the reservoir. Constant air pressure during flooding also aerates the growing medium. The sealed, airtight reservoir limits evaporation, which in turn prevents algae growth and keeps the nutrient fresh. The external pump reduces the overall cost of the system and helps prevent electrical accidents. You can use rockwool, coco coir, peat, or a composite growing medium with excellent results. Check out the Terraponic air table at www.fearlessgardener.com .

Growing is easy and efficient in this beautiful Visqueen-lined room.
Deep Water Culture (DWC)
    Growing in deep water culture (DWC) is simple, easy, and productive.
    If growing outdoors in a DWC garden, a simple overflow drainage hole can be cut in the side of the reservoir to prevent rainwater from causing it to overflow.
    Seedlings and clones are held in net pots full of expanded clay pellets, rockwool or other growing medium. The net pots are nestled in holes in a lid that covers the reservoir. The roots of seedlings and cuttings dangle down into the nutrient solution. A submersible pump lifts nutrient solution to the top of a discharge tube where it splashes into the access lid. Nutrient solution cascades down, wetting roots and splashing into the self-contained reservoir below, which in turn increases dissolved oxygen in the solution. Roots easily absorb nutrients and water from the solution in the oxygenated environment. Many gardens also keep an air stone bubbling new air into the reservoir to supply more oxygen.
    These gardens are simple by design and require no timer, because the pumps are on 24 hours a day. This low-maintenance garden is perfect for casual gardeners as well as hydroponic enthusiasts.

The simple air table design makes them low maintenance. Air is pumped into a reservoir filled with nutrient solution. The air pressure forces the solution up into the growing bed.

This ingenious DWC garden uses an air pump to aerate and agitate the nutrient solution.

Cutaway of the inside of a DWC garden
    Various emitters are available to apply nutrient solution. A single application point is common when growing in absorbent growing mediums such as rockwool and coco coir. Expanded clay works best when nutrient solution is applied via a large round emitter, several single emitters, or a spray emitter.

Always use a filter when using emitters. The filter will remove foreign objects that plug emitters.

Circular emitters apply nutrient solution all the way around the plant, so all roots receive adequate moisture.

Pressure regulated drip emitters control solution flow.

This emitter sprays nutrient solution over the top of the growing medium to aerate and disperse it evenly.

Mini sprinkler emitters are available in many sizes and outputs.

An array of different emitters connected to a main manifold shows the many different kinds of emitters available to hydroponic gardeners. Across the bottom are three different diameters of spaghetti tubes that dispense three different volumes of nutrient solution to plants.
Top-Feed Systems
    Top-feed hydroponic systems are very productive, easy to control, precise, easy to maintain, and efficient. The nutrient solution is metered out in specific doses and delivered via spaghetti tubing or an emitter placed at the base of individual plants. Aerated nutrient