Imbalances in the hardness/alkalinity ratio of water and Nile tilapia’s growth performance - doi: 10.4025/actascitechnol.v36i1.18995

Abstract

The present work determined the effects of water with unbalanced calciumhardness/total alkalinity (CH/TA) ratio on Nile tilapia growthperformance. Two unbalanced CH/TA ratios were tested for 8 weeks usingone indoor system with 30 circular polyethylene 100 L tanks and oneoutdoor system with 36 circular polyethylene 250 L tanks. The factorsand their specific levels tested were the total alkalinity of water (TA;50 and 100 mg L-1 CaCO3) and the CH/TA ratio of water (CH/TA; 1/2, 1/1and 5/1). In the indoor system, the 5/1 CH/TA ratio tanks had highertotal ammonia nitrogen (TAN) than the 1/2 or 1/1 CH/TA ratio tanks. Inthe outdoor system, higher concentrations of TAN were found in the 1/2CH/TA ratio tanks. The soil of the 5/1 CH/TA ratio indoor tanks hadhigher concentrations of organic carbon than the 1/2 or 1/1 CH/TA ratiotanks. The detrimental effects of the 5/1 CH/TA ratio on fish growthperformance were stronger than those associated with the 1/2 CH/TAratio. A significantly better food conversion ratio was observed in the1/1 CH/TA ratio outdoor tanks regardless of the TA level of the water.