Growth beds are a technique used for high-medium stem crops or for plants that produce large and / or heavy fruits. The aggregates used in these beds act as both a support for the roots of the plants, and by filtration, in theory, mechanical and biological.
In reality, the mechanical filtration of these aggregates may be less in cases where the density of fish is very high. For this reason and for safety reasons, it was decided to use a mechanical separator located inside the fish tanks.
The weak points of this technique are essentially two: the high evaporation of water and the weight of the aggregates. However, if you want to grow certain types of plants there is no alternative: even in the thematic area with stem trees the technique used is precisely that of the growth beds (in structure more similar to vessels that "read" real), in as the mechanical resistance of the is the only one of the cultivation techniques Acquaponica able to bear the weight of a tree from stem.
The structure of the growth beds (in the dedicated thematic area) will be made of laminated wood, covered with food-grade polyethylene, to ensure its hydraulic seal. There are a total of 4 growth beds, all of 0.70 meters x 4.50 meters x 0.30 meters in size; the inert selected is expanded clay, given its chemical-physical characteristics. The cultivation density that can be reached with this method depends strongly on the type of plant used: it ranges from a value of 6 plants / m2 in the case of watermelons, up to values of about 200 plants / m2 in the case of saffron.The siphon is fundamental in order to guarantee the movement of the water inside the system.
The siphon allows you to raise the water up to a certain level, allowing the roots of the plants to take all the nutrients present in it and, once reached the maximum height, triggering, allows the emptying of the tank sending the water towards the return tank.