Aquaponics

Life in the water: a team effort

How do aquatic animals and plants thrive in the same ecosystem? In short, this is possible due to the symbiotic relationship between their nutrient needs and the balance that exists between them. The same principle applies in aquaponics. An aquaponics system consists of two main tanks: one for fish and the other for plants. The fish are raised in tanks that recirculate water, ensuring they live in an environment free of toxins. This system is known as a recirculating aquaculture system or RAS. The plants grow in a water tray without soil, receiving their nutrients from the fish wastewater in the tray. When plants are grown this way—in nutrient-rich water without soil—it is called hydroponics. When recirculating aquaculture and hydroponics are combined, it creates aquaponics.

In aquaponics, there are two types of systems: coupled and decoupled. A coupled system, as shown in the graphic above, is one where water continuously flows from the fish tank to the plant tray. In contrast, a decoupled system, as the name suggests, does not have the fish tank and plant tray directly connected. Instead, in a decoupled system, the two components are separated, and fish wastewater is added to the plant tray at intervals rather than continuously.

When growing plants in an aquaponics system, there are three main methods:

Nutrient Film Technique (NFT), media beds, and Deep Water Culture (DWC)

The Nutrient Film Technique utilizes pipes, also referred to as gutters, to grow plants. These pipes have a shallow flow of water running through them, with holes in the top to place the plants. In this system, the plant roots are in contact with the water flowing through the pipe.

A media bed uses expanded shale, which is placed into the plant tray while water fills the remaining space. The shale is sturdy enough to hold the plants in place but still allows for water circulation.

The final method is Deep Water Culture, which is the method used by the BiG project. In DWC, the tray is filled with wastewater, and styrofoam boards are used to keep the plants afloat above the water. The boards have holes, and planting plugs are used to hold the seeds.