Success at last. My last canoe trip around my 1 acre pond revealed only a few small spots of Floating Heart which I quickly sprayed with Rodeo. My pond is 99% clear, 2.5 feet low, but the water quality is still good. Algae is at a minimum and almost all of the dead vegetation has been removed. The fish seem to be just fine; they feed voraciously in the evening (I am feeding only three days a week until my water level increases). A month ago I thought my work would never end and now my pond looks better than it ever has (with the exception of the low water). I can't wait until it fills back up with the future rains. At that time I will add one more dose of microbes. Glyphosate did the trick, with repeated applications and a lot of manual labor in removing the dying vegetation. Thanks to everyone for your advice.