Nutrient film technique (NFT) is another great way to hydroponically grow marijuana indoors. The concept is to have a very shallow stream or film of nutrient filled water running continuously over the roots of your cannabis plants.

Equipment required for the NFT method

Like every other form of hydroponics NFT starts with a reservoir. A reservoir is simply a container for pH-balanced water to which the proper amount of nutrients for the life and stage of the plants has been added. Such a container might be a 5 gallon (23 liter) bucket, a 10 (46 liter) gallon plastic or rubber tote up to a 50 gallon (115 liter) drum.

Next you will need at least one aquarium style water pump. The GPM (gallons per minute) flow rate will be dependent on the size and number of plants you are feeding. An adjustable pump is best.

An air pump and one or more air-stones are needed to properly aerate your reservoir. This will provide plenty of fresh oxygen to the roots.

A flat table or a series of plastic gutters on a support frame is required to hold your plants.

Any hydroponic medium may be used, but rock wool is the favorite followed by absorbent matting.

You will also need ¼ to ½” poly-vinyl tubing and PVC plumbing fittings and pipe for the return line.

The tray or gutter frame support

Trays of many standard sizes many be purchased from most hydroponic stores. Vinyl gutters are available at larger hardware stores. These will be placed on a frame strong enough to support full-grown marijuana plants. The frame must be built higher than your reservoir at a roughly a 3-5 degree slope so that gravity will pull the water down the table to your drain pipe.

Running the nutrient film technique (NFT) system

Attach your air stones to the bottom of your reservoir with suction cups, glue or weights. Run the tubing from your air pump to your air stone(s).

Fill your reservoir 2/3 full of water. Add nutrients as per manufacturer’s suggestion. After mixing, test both the pH and the PPM. Balance and adjust as necessary.

Step by step setup of the NFT

1. Now go ahead and turn on your air pump. You should have a nice froth of tiny bubbles.
2. Attach the main feed line to your water-submersible water pump and place it in the bottom of your reservoir. Attach the other end of the main feed line to a splitter.
3. Attach the smaller drip tubes to the splitter and run several equally-spaced feeders to your table or one line for each gutter.
4. Align the gravity return line so that the water will flow back into the reservoir.
5. Turn your water pump on its lowest setting and check for leaks and proper, even flow throughout the system.
6. Once everything looks good, slowly increase the water flow until the table or gutters have a steady uniform coverage of water (or film) roughly 1/8” to ¼” deep.
7. If using matting, then place that in your table now and add your plants or place your rock wool cubes with marijuana seedlings or marijuana clones in your gutters. Allow enough spacing between plants to allow them to grow to maturity.

That’s it! No complicated timer is needed for the nutrient film technique (NFT) as we shall be running both pumps 24 hours per day. Now just monitor daily and watch them grow like, well – weeds! Check the pH and the PPM of your monitor every few days and adjust if necessary