THE USE OF ZEOLITE FOR WATER QUALITY MANAGEMENT IN COLD WATER RECIRCULATION AQUACULTURE SYSTEMS
This study was performed to evaluate use of zeolite for water quality management in cold water recirculating aquaculture system. The system was reared Arctic charr (Salvelinus alpinus) and Hybrid char (Salvelinus fontinalis × Salvelinus alpinus) fry. Fish biomass in the reservoirs was distributed as follows: Arctic charr accounted for 7.32 kg at a density of 23.74 kg∙m-3, and hybrid charr accounted for 7.78 kg at a density of 26.91 kg∙m-3. After increasing the feed rate and documenting water quality studies, a vast increase of ammonium and nitrite concentration was noticed in the rearing tanks. Natural zeolite, known as clinoptilolite with a cation exchange capacity (CEC) of 1.20–1.50 mol.∙kg-1, was used to reduce the amounts of these hazardous substances in the rearing tanks. Zeolite was used to decrease the increased concentration of ammonia and nitrites, which were reduced by 22.7% and 16.7%, respectively, during the study period. These results suggest that zeolite is suitable for water quality management in cold water recirculating aquaculture system with as little of an investment as possible.