Marijuana Horticulture Fundamentals. K of Trichome Technologies
to the top of the rockwool cube to prevent algae growth on the top of the cube like in this photo.
Photos: K
This system uses a ¼-inch drip line and ¼-inch drip line elbow to water a three-inch rockwool cube. The ¼-inch drip line is attached to a ¾-inch feeder line that goes back to a water / nutrient reservoir that has a water pump in it that delivers water and nutrients to the dripper at predetermined times, several times a day. The reservoir is full of filtered, oxygenated, non-chlorinated, nutrient-rich water.
This is another good example of a deep water culture (DWC) / nutrient film technique (NFT) system. It is also fairly simple to construct, using only materials from your local hardware store. The system is based around six-inch polypropylene tubes enclosed on both sides and slightly tilted toward the center. On the low end of the sealed tube there is a one-inch drain that drains all of the water from the 10 tubes into a water reservoir. A common submersible water pump delivers water/nutrients via ¾-inch tubing that connects to a ¼-inch drip line, which constantly feeds water and nutrients to the base of the individual plants. The plants are cultivated in 3½-inch mesh baskets covered in clay pellets (Hydroton). Water and nutrients run through the baskets and clay pellets, past the plant roots, to the bottom of the tubes. In the bottom of the tube sits two to three inches of water that is constantly aerated using common aquarium air pumps and air stones. When the water builds up to the desired level (of two or three inches) it naturally overflows back into the reservoir to repeat the process (recirculation). The water flow must be constant and there must always be water present in the bottom of the tubes.
Deep water culture / nutrient film technique system.
Water temperature is crucial in a DWC/NFT system.
Photo: Freebie
Note that water temperature is crucial in this system. Too hot or too cold and your plants are fucked! Put more technically, this can result in growth stunting, root rot, etc. Heat your water by using titanium aquarium heaters; cool it by using a water chiller. The perfect temperature for this system’s water is 72°F at all times, day and night. In this system the water must continually recirculate, 24 hours a day, otherwise the roots dry out or the water gets too hot, causing plant stress.
This type of DWC / NFT system requires the constant watchful eye of someone able to spend a lot of time monitoring the system; mostly this involves checking to see if all equipment functions and plant parameters are acceptable. This is not a system for someone with little time to spend in his or her garden. Nutrients must be replaced every week to ensure there is no depletion of required nutrients or minerals. That said, it is a fairly simple system to operate—you just have to be vigilant in watching for problems—and to clean, maintain, and tear down for storage. There are many systems like this available on the market but I prefer to build my own.
CO2 injection tubing surrounds this system and oscillating fans are placed underneath so that air flow and CO2 levels remain perfect. Reflective Mylar panels also surround this system to reflect any stray light back into the growspace.
The silver aluminum tubing at the center of the system is attached to extraction fans that periodically extract any hot or stale air that may have accumulated in the grow tubes, thus ensuring higher oxygen levels for the root system. Drink cups are placed in empty holes to prevent unwanted algae growth inside the tubes; without light algae cannot grow. This system can be raised or lowered to almost any desired height, which can be an advantage to those with impaired mobility.
This system is primitive, yet very efficient and low maintenance. It is the same “shelf system” design that has been described previously, except for the drainage. The one-inch drain (for runoff water) is connected directly to a three-inch PVC drainpipe that leads directly to the municipal sewer system, which means no draining of water collection reservoirs. The runoff water simply goes away without you having to do anything, which decreases the amount of work you will have to do every time you flush or water. The PVC drainpipe can be seen at the end of the shelf system in this picture.
Run-to-waste systems are very low maintenance.
Pots lined up on a run-to-waste system.
Photos: Samson Daniels
This is another example of a drip system, except that it uses expanded clay pellets (Hydroton) as its exclusive medium. The rooted clones are placed in a two-gallon pot that is ⅔ full of clay pellets, at which point the pot is topped off with more clay pellets and drip feeders are placed at the base of each plant to deliver water six to eight times daily, depending on the growth cycle; plants on an 18 hours on / 6 hours off light cycle require more water than plants on 12 hours of light. A submersible water pump, placed in the reservoir beneath the table, delivers the water and nutrients to the plants; a multi-cycle timer turns it on and off at the desired times each day.
I recommend this system only if you have lots of spare time to decontaminate and clean all of the clay pellets between harvests. This system requires a constant water temperature of 72°F or else root problems could occur. A keen eye is required. If the power goes out or the water pump breaks you will have minimal time to repair them or else the plants will die from lack of water; expanded clay pellets hold little to no moisture—their chief purpose is to hold the plants upright and provide ample space for air, water, nutrients, and roots to interact. If simplicity is what you are looking for then this is not the system for you.
Drip system with hydroton. Keep water temperature at 72°F or else root problems could occur.
Photo: K
This is a classic example of an ebb and flow system. Rooted clones are placed into six-inch rockwool blocks and the blocks are placed into two-gallon pots; the rockwool blocks are then surrounded by expanded clay pellets to add support for the blocks. A water pump is under the table in a reservoir, as described previously; it delivers water and nutrients to the plants by flooding the whole black tray to a depth of 4–6 inches for a period of 5–10 minutes. An overflow drain prevents the water from ever exceeding desired levels. The water and nutrients then drain back in the reservoir for reuse. The cycle is repeated 4–6 times a day depending on plant growth stage. A multi-cycle timer controls the water pump; when the pump stops, the water immediately returns to the reservoir with the help of gravity. The nutrients and water need to be replaced at least every week in a system such as this in order to keep all the nutrients available to the plants.
These plants are thriving in the ebb and flow system. It is simple