NFT (
nutrient Film Technique) systems are the most productive for fast growing plants like bib lettuce. They operate on a very simple principle. The roots grow into a shallow mat located in a light-tight draining grow bed. Nutrient solution flows over the roots up to 24 hours per day. The majority of the roots actually grow on top of the thin matting. The nutrient solution flows slowly over the roots. This system allows the most air and
nutrients to be absorbed by the roots.
ebb and flow or Flood and Drain systems work well for longer season plants like tomatoes. This system works when water floods into the bed, usually from the bottom, pushing the CO2-rich oxygen- poor air out. When the medium drains, it draws the new oxygen-rich air into the
growing medium.
Top feed systems apply the nutrient solution to the base of each plant with a small hose. The solution is aerated as it flows through the air.
The one thing that you will notice in all three of these systems is oxygen that is applied one way or another to the roots for healthy plant growth.
Ron