Cecil, the test methods do not take into account the PP absorption by the organics on the bottom. Hopefully the amount from your calculations will be enough to keep the pond pink long enough to get the job done. After application and mixing, if pink does not persist you will know why - absorption by benthic organics.
You know I thought about that Bill. Not sure what to say but the publication above seem to indicate a demand test for the water will do the job.
According to the publication another way to do it is to add 2.0 mg/l, and if the water does not stay pink within 8 to 12 hours to add another application. We do know from the demand test 2 mg/l would not be enough.
Perhaps the problem is adding enough to potentially negate absorption by benthic organics could be too stressful on the fish???
