Abstract
This research was conducted to investigate the effect of intermittent water pump operation on nutrient uptakes and plant growth yield in an aquaponics system. Four backyard size aquaponic units were build using the same type of hydroponics grower known as media grow bed. Four different types of water circulation system which are, (a) 2 h on and off (2HWC), (b) 4 h on and off (4HWC), (c) 8 h on and 16 h off (8HWC) and (d) 24 h on (24HWC) of the pump were implemented on the aquaponic units. Cocopeat was used as the substrate. A compact water filtration system containing mechanical and biological filtration units was used in this study. Water quality (ammonia, nitrite, and nitrate), plant yield, and fish growth were all measured weekly during the twelve-week experiment. Other parameters measured include pH, water temperature, dissolved oxygen (DO) concentration and total suspended solids (TSS). The result revealed that pH, water temperature, TSS and DO values remain within the acceptable range for growing Gynura procumbens (G.procumbens) and culturing of Oreochromis spp.. A good conversion rate of ammonia into nitrate was obtained using a compact water filtration system. The highest increment in plants height and leaves production could be seen in 2HWC where the percentage of G.procumbens growth was 377 % (height) and 960 % (leaves) throughout the cultivation period. The highest yield of fish growth was also found to be in 2HWC (211 %). 31.5 kW (50 %) energy could be saved using 2HWC as compared to the control (24HWC). This result could be used in conserving the energy of aquaponic farm growing herbs and tilapia. Future research needs to be conducted to determine its suitability in conserving the energy of aquaponic farm growing other types of plants and aquatic animals. Lower energy consumption in aquaponics system reduces the high cost associated with small aquaponic farm and increase profit in the long-term run.
