Fig. 1 illustrates the experimental setup. It shows the
recirculating aquaculture system which consists of fish tanks,
bio-sump tank, hydroponic units and pumps under two greenhouses.
The system consists of five rectangular concrete tanks that used
for fish culture. Dimensions of each tank are 8 m long, 5 m wide and
1.5 m high. The water volume in each tank was 40 m3
. Each tank has
an inlet pipe and two types of outlets pipe. The inlet pipes for
adding fresh water to fish tank, two types of outlets for one of them
is a mechanical spillway which carries the normal expected water
flow from the tank and can be designed to either partially or
completely drain the tank to facilitate harvest. The second one is an
emergency spillway which used to remove the exceed water
capacity of tan