Results and discussion
The values of water physico-chemical parameters, in the recirculating aquaculture
system, registered values within the optimal range for both rainbow trout and
spinach (Table1).
ิby analyzing the values of main water quality parameters throughout the
experimental period, it can be said that water temperature, pH and dissolved
oxygen were maintained within optimal range for both rainbow trout and spinach
(Nores variety) growth. Monitoring electrical conductivity will remove most of the
guesswork in meeting the spinach nutritional needs (De Boer et al, 2012). It is well
known that EC is an effective way to estimate the fertilizer content via salts. In our
case, electrical conductivity registered slightly higher values, but similar to other
authors as AL-Hafedh (2008). Ammonium and nitrites values were situated within
the optimal range for the technological requirements for growing rainbow trout.
Nitrate values were slightly higher, in agreement with Colt et al, (1981).
Regarding nitrite content in the consumable part of spinach from the initial batch,
an average value of 0.61±0.074 mg/kg fresh weight is registered. Also, the nitrite
content in V1 variant is 1.21±0.071 mg/kg fresh weight, 2.26±0.098 mg/kg fresh
weight at V2, 2.24±0.085 mg/kg fresh weight at V3 and 0.93±0.11 mg/kg fresh
weight at conventionally cultured spinach, Cv control variant (Figure1)