The paper by Dr Paul R Adler is interesting, but I have the following questions.

1.    The major objective of the paper was to reduce the level of P from an
effluent of Rainbow trout by growing plants such as lettuce in the effluent.
Then the water with low P level can be used again with a bonus of marketable
lettuce. If that was the case, what will be the effect of P to the Rainbow
trout when they are grown in water with high level of P? The introduction
did not give solid reasons as to why P has to be reduced to low level.

Knowing this, I might then understand the justification for this study. In
fact, under the heading, "Rainbow trout effluent characteristics," the
effluent had the lowest P value (0.7 mg/L) when compared with the content of
NO3-N, K, Ca, Mg and S. So, why was P targeted for reduction?

2.    In characterizing the effluent the following values were given:

            NO3-N = 25 mg/L
                    P = 0.7 mg/L
                    K = 5 mg/L
                   Mg = 20 mg/L
                    S = 9 mg/L

These values do not mean much without stating the number of samples taken
and the value of the standard error.

My regards.
Dr Zecarias Russom Tesfasion
ABUBAKAR TAFAWA BALEWA UNIVERSITY
P.M.B. 0248 BAUCHI, NIGERIA