Ok, an update. After using one application of fluridone, captan and cutrine, colorant and an aeration system, (and God's grace of course since I was almost shooting in the dark) my pond is a beautiful pea green with no sign of algae, duckweed or other nasites. I don't know what did it but the aeration system I got from the ebay vendor is so far kickin' butt. It uses the "soaker hose" aerators so I will watch them for problems. I am trying to include a pic to show what it looks like now. Thanks for all the advice and especially to Sue Cruz who told me to look for a better vendor. This guy was more than willing to return my call and talk at length with me on how to use the setup.
