My pond is about the same size as yours Danny, at 11 ft in the middle. I added bacteria/ enzymes at the end of summer as well.

There was a brief period of cold where I shut the system off completely due to 20* weather and within a couple days I had a pea green film over the entire pond. I doubt it could be anything but BGA. That is my major concern due to having critters running the yard during the day.

.10 surface acre pond, 10.5 foot deep. SW LA. The epitome of a mutt pond. BG, LMB, GSF, RES, BH, Warmouth, Longear Sunfish, Gambusia,Mud Minnows, Crappie, and now shiners!!...I subscribe!!