Those look like nice GC. I think you got a good deal for the size. Not sure why you are so concerned about o2. If you are spot treating with Aquathol Super K just treat your pond in sections splitting the treatments. Our crews use a new product called Aquastrike which is liquid endothall and diquat and it knocks out coontail fast. We also have application boats and systems to allow for a more accurate treatment but pond owners use the liquids all the time. I think you should look at using fluridone especially with introducing new GC I'd be cautious using products you are unfamiliar with. At least with Fluridone you will get all the coontail with lowering the o2 depletion issue.
