That is what I'm worried about and all I'm worried about. Keeping the water flowing was keeping the ice clear on enough to exchange gasses, even as it sits now there is only an inch or 2 of ice on the surface, it does not get cold here for long periods of time. It's cold for a week and then in the 40's and sunny for weeks on end. Pump is running again and flowing water is clearing up the ice. I'll add a de-icer tomorrow.callingcolleen1 said:t worry enough about the fish getting smothered under too much ice for too long.