In T2, we used dosages of up to 0.16 g/L of calcium hydroxide;
however there was no inhibition or decontrol of the nitrifying bacteria
groups because the nitrification was similar to that of T1 and T3.
NO3–N accumulated during the experiment in all treatments, and
the mean concentrations remained below 60 mg/L; however, all
treatments showed maximum values of above 60 mg/L. Kuhn et al.
(2010) reported the negative effect of NO3–N on the L. vannamei
growth and survival when in concentrations N220 mg/L and at low
salinities (≈11‰). In T4 there was a reduction in the NO3–N values
during the last 20 days. This is likely a result of denitrification, in
which anaerobic bacteria convert nitrate into nitrogen gas (N2; Van
Wyk and Scarpa, 1999).