Water rich in nutrients is circulated through long channels at a depth of about 20 cm while the rafts (usually polystyrene) float above. Plants are supported inside holes in rafts. The roots of plants hang in nutrient-rich and oxygenated water, where they absorb large amounts of oxygen and nutrients that contribute to rapid growth conditions.
This method is the most common in the field of large-scale distribution, when it is intended for the cultivation of a specific crop (typically lettuce, salad leaves or basil) and in which there is a high density of fish (up to 10-20 kg of fish per m3 of aquarium). However, it can be adapted to a low density coefficient of fish production.
Water flows by gravity from the fish tanks, through the mechanical filter and into the biofilter. The water is pumped in two directions through a "Y" connector. Some water is pumped directly into the fish tank, the remaining is distributed equally through the channels. The water flows, always by gravity, through the growth channels in which the plants are found and then exit the channels and returned to the biofilter, where it is again pumped into the tank or into the fish channels.
However, when using a low fish density, the DWC can be designed without using external mechanical or biological filtration containers. In this system, water flows by gravity from the fish tanks directly into the DWC channels.
The main advantage of the DWC is the amortization of all initial expenses.
This is a valid alternative for novice growers interested in growing out of soil. Also, let's not forget that the most important results will be at harvest time. A higher absorption of nutrients also means plants with higher quality tops, higher yields and a more intense "high". A cultivation in soil can never compete with a hydroponic cultivation, since the roots do not receive the same amount of oxygen as a constant flow of air. Furthermore, it is a system that can be expanded. The principle is the same for the cultivation of more plants.