Russ I would think that if your visibility decreased from 39 to 20 and it was not due to turbidity from rain, change in aeration or other source then that indicates an increased plankton bloom. That would be a normal summer occurrence. Aeration while good for water quality can through circulation reduce plankton bloom and its visibility at the surface. The fact that you saw blue green color is another indication of a bloom. Visual color is an indication of plankton bloom usually noticed when the color increases or appears in spring/summer. Unless one has a sterilized pond there is plankton present and it is only a question of which types , density and color (if visible with the eye) even in winter.

On the forms we turn in for soil tests it has a blank to fill in for why you want the test i.e.. , corn , cotton ,trees, ponds mgt. etc. I am not a good enough chemist to translate your test results to a pond application. It is very good data to have as a baseline and PaPond, Bill , Dave, Bob or others may be able to extrapolate it to your pond. If they don't I can probably find some info. A good source would be your extension agent for ponds.