That GC stocking rate is 10-15 per acre too many unless you have underwater vegetation that the GC like to eat. First identify the problem, then treat it. It's like going to a dentist and saying "pull all my teeth because I know sooner or later they might have a cavity in them all".

GC like and dislike different plants. They will eat some, and not others.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).