Ammonia nitrogen (ca. 40 g/L) and nitrate (ca.18 mg/L) concentrations were not significantly different amongst treatments, althoughmean nitrite concentration in the control tank (13.00 ± 0.79 g/L)was significantly higher than either low or high ozone regimes(8.89 ± 0.96 and 6.17 ± 0.78 g/L respectively; Fig. 2B, ANOVA,P < 0.01).