MN,In your size pond of .5 acre and unless you are very overstocked and/or have a lot of organic matter I would shut it off for now. This is a transition time for midwest and northern ponds. Rapid water temperature change is very stressful even for cold water types.If you get snow cover for 2-3 weeks then consider starting it back up.Most diffusers will melt 4-6 inches of ice off in 24 hours with as little as 1-2 cfm. Anytype of diffuser even in shallow water can super cool the warmer deeper water quickly in a small pond.If your pond was 2-3 acres I might alter this somewhat.We had 67F in NW Ohio yesterday and 4 inches of rain overnight. Today the temps are headed for 26F tonight and 16F tommorrow with 60 mph gusts and 30 mph sustained. This will over circulate most ponds and cool them too fast. This same weather picture happened last year the first week of December and any 1-3 inch readear we stocked in November did not survive. Can not do much about mother nature but when you have some control and choice such as when to aerate and when not to take advantage of it.