Measure bloom with a secchi disk. If the reading is less than 12" and it is due only to the bloom, then something should be done. If that's the case, then I'd treat portions of the pond with Phycomycin or a similar product.

A phytoplankton bloom is the base of the food pyramid in a pond.

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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).