UPDATE: I finally was able to get on the pond last week and have some more accurate information. I come in just under 1.5 surface acres with an average depth of about 5.5' - 6'. My visibility has actually increased since throwing the 160lbs of granulated gypsum in to about 4". Still not very good, but better than the 1" we had before.
I have 2500lbs of powder gypsum coming. Where I am confused is that I have had some biologists tell me 500lbs would be more than enough, the pdf ewest linked says anywhere from 1000 - 3000 lbs an acre and Rainman suggests 2-6 tons to notice a difference, if any. Why is there such a variance? Do I just need to find the right formula for my pond?
