Different biofilter media and water quality fluctuation in an integrated hybrid tilapia (Oreochromis sp.) - loose leaf lettuce (Lactuca sativa var. crispa) production system

Abstract

Integrated aquaculture-hydroponics systems were operated in closed recirculating system without daily discharge of water or organic matter during 35 days of culture period. During the culture period, three kinds of biofilter media (broken shells, charcoals and gravels) were evaluated for their efficiency in relation to biofilter efficiency (E), water quality and filter media economics. Specific growth rate (SGR) and survival rate of hybrid tilapia ( Oreochromis sp.) as well as fresh weight ofloose leaf lettuce (Lactuca saliva var. crispa) were investigated. The trickling filter combined with the nutrient film technique (NFT) accomplished the biological filtration in maintaining water quality for tilapia culture system. Results showed that pH and total ammonia nitrogen (TAN) concentration of rearing water differ significantly (P < 0.05) among the filter media during five weeks of experiment. There were significant differences (P < 0.05) among the treatments in unionized ammonia (NH3-N) concentration at initial stage, third week and forth week of the experiment.