Nutrient film technique
Film
A shallow, slow stream runs along a covered channel while roots hang in moist air, then into the flow
Channels
Common trays are 4 to 6 inches wide and tall, with net pots in the lid
Oxygen
Aerate the reservoir with circulation, stones, or sprays. Some growers add stones in the tray
Misters
Extra spray in the headspace keeps humidity high above the film
Tank size
About 25 gallons per 600 watt lamp keeps pH and strength more stable than a tiny tub
NFT limits
Small plants
Best for compact crops. Huge root masses clog the channel
Support
Channels do not brace a heavy stem. Large plants tip without a screen or stakes
LECA variant
Pots of pebbles in a wider tray, with a continuous drip down the stones, avoid some clogging
Shallow pool
A 1 to 2 inch drain stand keeps a thin film under pots if roots leave the container
Aeroponics
Mist
A 10 to 20 micron spray hits bare roots with highly aerated droplets
Hold
Plants sit in 2.5 to 5 inch baskets of rockwool or LECA over a tube or tray
Pump
About 60 psi makes a fine mist. Weaker pumps make a coarse spray
Cycle
A common timer pattern is 1 minute on and 3 minutes off
Drain
Slope about 2.5 percent. Steepen it if roots dam the return
Risk and hygiene
Clones
Most reliable aeroponic use is a small cloner, not a full flower room
Failure
If nozzles stop, plants can collapse in hours. Few growers finish a crop this way
Support
Roots do not anchor, so use bars or a screen
Sanitation
Some growers add dilute hydrogen peroxide on a short interval, or pass solution through a UVC sterilizer
Watch
Check nozzles and roots often. This method has almost no buffer