From our friends at HowToGrowMarijuana.com:
Choosing a Growing Medium
This is the substrate that replaces the soil. Some hydroponic systems like Deep Water Culture don’t require any medium at all. For others you can choose between many different options including Rockwool, perlite, clay pellets, coco fiber or a combination of these. To help you choose the best medium for your set-up, check out our page on growing mediums here.
Choosing a Hydroponic System
There are so many different types of hydroponic systems for growing marijuana indoors. From the basic wick method which does not involve any pumps at all to the more intricate Aeroponics method with full misting emitters, there is an option for every grow room design and every level of expertise.
With any hydroponic system, your goal is to promote healthy roots, because healthy roots = big, healthy buds.
· 1. Aeroponics – The roots of the marijuana plant are held in a water tight, dark box with small nozzles emitting a fine mist of nutrients over them. This gives a humid but oxygenated area for the roots to flourish without being completely immersed in water.
· 2. Continuous flow– Or the Top Feed system. This is a common DIY hydroponics system which uses a PVC pipe with holes cut at intervals. The young marijuana plants are grown in the holes, and water with nutrients continuously runs through the pipe.
· 3. Deep Water Culture (DWC)– The roots of your plant are situated within the nutrient solution. Remember, roots need oxygen. In a DWC set-up you need to add an air stone to oxygenate the nutrient solution.
· 4. Drip Irrigation– A very effective way to grow with small emitters dripping the nutrient solution directly into the pot near the roots. This saves water, evaporation is near zero and it is highly effective as the roots get nutrients and also air.
· 5. Ebb and Flow– The Ebb and flow system works with your plants sitting in a tray above a reservoir of nutrient solution. The nutrient solution flows into the tray, the roots take what they need and the rest of the solution flows back into the reservoir below.
· 6. Nutrient Film Technique (NFT)– Similar to the Ebb and Flow situation above but the tray is tilted so the nutrients are a thin film of liquid and constantly flowing past the roots.
· 7. Wick system– The marijuana plants are in pots which can have any grow medium in them, including soil (granted, then it’s not technically a hydro system). A thick wick of cotton connects the pots to a reservoir below. The roots can suck up the nutrient solution as they need it via capillary action.