High algae count can limit sunlight penetration, which plants and phytoplankton use to mfg O2.

Floating mats of algae, or phytoplankton? I'm assuming you don't have an aeration system in the 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).