Dear Paul

I wish to remark on Dr Zecarias Russom Tesfasion question to you which I
could interesting and that has not received a full answer to it.

Zecarias summarised:
>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.

Zecarias asked:
>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.

this means that is if Rainbow trout can grow in higher P in its cultivation
tank and you are not releasing the treated water into a river, then the
recycled water that goes back to the fish tank need not have such a low
level of P. This means that higher P in the effluent will permit the use of
conventional hydroponic lettuce production methods.

Thus the question is:
why do you have to still try to achieve such a low P (if you are going to
recycle the water into the fish tank)

jacky foo
unesco microbial resources centre, stockholm