The water quality of the 3 recirculating systems is summarized in
Table 3. In general, the LOW accumulation RAS differed in most water
quality parameters from both the HIGH and MIDDLE accumulation
RAS. The LOW accumulation RAS had the lowest levels of conductivity,
dissolved CO2, COD, TAN, NO3-N and orthophosphate-P and the
highest levels of pH and dissolved O2. The HIGH and the MIDDLE
accumulation RAS were similar in water quality except for pH,
conductivity and COD which were higher in the HIGH accumulation
RAS. Alkalinity was higher in the LOW accumulation RAS differing
statistically only from the MIDDLE accumulation RAS (P=0.010).
NO2-N was equal for all RAS (P>0.05).
The denitrifying reactor in both HIGH and MIDDLE accumulation
RAS performed similarly (P>0.05).