View the slideshow to see the evolution of the construction of my system. Nutrient Film Technique or NFT is a well known technique in hydroponics.
It is probably where modern AquaPonics, the combination of Aquaculture and Hydroculture originated.
A shallow stream of water is recirculated in a channel past the bare roots of the plants. This water contains all the dissolved nutrients that plants need for their growth.
In my system, I have located the sump next to the fish tank with a growbed on top that serves as biofilter. This growbed ensures that the solids are removed before the water is led to the gutters. This is to prevent clogging of the plants's roots. As an extra precaution, I intend to only grow fast rotating vegetables like lettuce in this system.
The location of the sump next to the fish tank allows both the fish tank and the gutters to overflow into it. The pump leads the filtered water to an upper gutter from which it is split in two directions: one part goes to the NFT channels, another part returns directly to the fish tank. This ensures constant recirculation, constant removal of solids and constant aeration.
This is very important: it is the solids that pollute the water and the bacteria that grow on them are competing with the fish for oxygen.
Constant removal of solids results in better water quality and healthier fish.