David, it is amazing how great blues find the holes in the fishing line fence. It may take them a day or a week but they do fine the weak spot. That is why i went to the deer netting. I also have not lost any fish due to the cold, even with 5 inches of ice on the surface. I turn off the pumps so the fish can conserve their energy in the cold water. Add a bubbler at one end to make sure there is enough oxygen getting into the water and then wait until the water is above 50 F before starting the pumps back up. I do a cleaning each spring to remove leaves and excess muck. then with the filter and the UV things go pretty smoothly the rest of the year. I do have to unplug a pump now and then.