The study showed that 90L of pond water per irrigation supplied on average 205, 327, 19 and 34mg of TAN, NO3−nitrogen, SRP and TP per hydroponics unit, respectively. Filtration reduced total suspended solid content in the pond water by 61%. Use of filtered water increased lettuce yields by 87, 63 and 52% in the control, gravel, and sand treatments, respectively. The highest head weight and lettuce yield were observed in the sand treatment followed by gravel and the control treatments respectively. The current study showed that despite the limitations such as high amounts of waste solids that water from earthen ponds may pose in terms of re-use for hydroponics, in order to improve yields, it is appropriate to filter the pond water. The study showed that sand culture is appropriate for hydroponic vegetable production using nutrient rich catfish pond water.
The results demonstrated the potential re-use of catfish pond water and provide options to optimize utilization of the pond water nutrients and be able to recycle high turbid earthen pond water. Removal of solids and nutrients in the pond water would reduce the pollution potential of such water if discharged to surface waters. The application of such information will be relevant in many countries where fish are produced and cultured in earthen ponds. Further studies on supplementation of macronutrients and the effect increased irrigation frequency would provide sufficient information to develop refined design criteria for the use of catfish pond water effluents in integrated catfish-hydroponic vegetable production.