Pond water depth was maintained at 1 m, which
was recorded weekly and water loss through seepage
and evaporation was refilled weekly. Water samples
for quality analysis were taken from a platform at
the center part of each pond with a 1.5-m long PVC
tube column sampler for integrated full depth samples.
Concentrations of dissolved oxygen (DO) and water
temperature were measured in situ bi- weekly with a
portable meter (YS1 Mode1 57) at 25 cm below the
surface at 0600 (dawn) and 1500 hr, approximately
representing low and peak level during a die1 cycle.
Phytoplankton production was measured bi-weekly
as chlorophyll u, which was extracted with 90%
acetone from samples concentrated with GFIC filters
and determined spectrophotometrically following the
Standard Methods (APHA et al., 1989). Total ammonia
concentration was also analyzed bi-weekly by phenate
method (APHA et al., 1989).
Data were analyzed for treatment difference using
t-test (p < 0.05).