Performance analysis of aquaponics system for longifolia lettuce production in different growth media

The aim of the present study on the performance of aquaponics systems is to provide a solution to several sustainability issues and obtain organic food free of chemical contaminants. Where, the water quality for rearing Nile tilapia fish is evaluated in three tanks (T₁, T_2, and T₃). In addition, assess the best growth media of the lettuce plant (Lactuca sativa) in boxes of wood, such as the first box was Crushed Stone (CS), the second box was Crushed Gravel + Crushed Stone (CG + CS), and the third box was Crushed Gravel (CG)) for growing lettuce and also used as a filter to improve water quality. The main experimental work of the present study was carried out during the period from September 2022 to April 2023. The experimental system was designed, fabricated, and implemented in the laboratory at the Al Gamaleya Center (31°51'56.7 N and 31°10'44.2 E), Dakahlia Governorate, Egypt. Fish growth parameters were measured in terms of weight and weight gain weekly, and fish growth indicators and water quality indicators of the system were calculated weekly in the three tanks for 17 weeks, and also lettuce crop quality indicators were measured for the three boxes. For water quality indicators, dissolved oxygen (DO), toxic ammonia (NH_₃), pH, temperature, total dissolved solids and electrical conductivity were analysed. In addition, lettuce growth parameters were measured in the three boxes with the three different media by leaf number, leaf width, leaf length and root diameter. The effect of fish growth environment (tanks), time, and their interaction as independent variables on water quality indicators were studied. The results indicated that growth rate for fish and lettuce was better in the third tank and third box respectively. However, the current results also showed that the levels recorded in the three tanks for water quality indicators do not exceed the permissible levels required for fish farming and production, but third unit (tank + box) had the best overall result for all parameters under study and where, it was the best in general. The most important results of this analysis were the significant p-values for the indicators NH₃ and DO with T, and t. The interaction T*t was not significant for DO and significant for NH₃. The R² values were 0.914 and 0.873 respectively for the growth indicators as follows: NH₃ and DO respectively.