The issues that I've had with the smaller openings in the plastic objects (snow fence included) is that if you don't control the FA in the pond, it will grow enough to obstruct all the openings.

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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).