Note
The objective of this research was to determine the nitrification rate response in a perlite trickling biofilter (root growth medium) exposed to hydroponic nutrient solution, varying NO−3 -N concentrations, and to pH levels optimum for plants (6.5) and nitrification (8.5). The experiment used recirculating tank batch culture and was based on typical startup characteristics for bringing biological filters up to full capacity in aquaculture systems. No significant difference (P value < 0.05) in nitrification rate was found when recirculating system water contained no nutrient solution versus a complete hydroponic nutrient solution or NO−3 -N concentrations of 0, 100, or 200 mg/L.