Dissolved oxygen and temperatureweremonitored twice daily; and
ammonia, nitrite and nitrate and pH were monitored once a week. Dissolved
oxygen and water temperature were monitored with a YSI 55
oxygen meter. The pH was measured using a digital pH meter Alfakit
AT350 using the electrometric method. The concentrations of ammonia
(NH4
+/NH3) − N, nitrite (NO2) − N, nitrate (NO3) − N, were analyzed
using the colorimetric method according to procedure described by
Strickland and Parsons (1972).