This year, ponds that I fertilized in this area are still green with a bloom. Ones that I didn't fertilize are showing what you are seeing. I don't think dispensing 2# of a water soluible fertilizer specifically for ponds will do any harm, and it might help. I don't know how well it will work tho. Do you have underwater plants showing up?

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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).