Performance of a small-scale modular aquaponic system
Aquaponic systems aim to exploit the advantages of aquaculture and hydroponic systems. A reasonable fish production can be sustained and at the same time a wide range of green plants and vegetables will be beneffited from the nutrient-rich outflow of the fish tanks, providing nitrification services to reduce the ammonia and nitrite loads. In this paper, the performance of a small-scale modular aquaponic system was assessed for the critical initial running period of 14 days during September 2011, using lettuce, basil and Nile tilapia. It was evident from the results that mid-range fish stocking densities and accordingly nutrient loads are able to support a plant harvest at a ratio of 1:4 to 1:5 (amount of fish feed provided: harvestable biomass) in both species, depending on the initial size of the plants. Very small plants with sensitive root system should be avoided, as well as increased ammonia loads. Further improvements could be achieved by fine-tunning of the flow characteristics of the system, the standardization of water quality profile, the appropriate selection of substrate and the addition of extra biofiltration compartment.