Up nort dere, I'd move the diffuser to shallower water - 4' depth to preserve the warm 39�F water when the pond is iced over and you're running the diffuser to keep the water open.

If you have a float and a rope marking the diffuser, it should be an easy propositon to drag the diffuser to shallower water.

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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).