There are options other than LMB but they take work. In addition to the HSB and SMB you could (because of the pond size) use 1 of several predators to aid in the BG control. You could use 1 FH catfish stocked an about 6-8 inches understanding that you would have to remove it at about 7-8 lbs. Same concept with other known predators as long as they can't reproduce/cross with others present.