You will have to decide for yourself if you want the headache of keeping a running pond going in a freezing climate. I mean having a waterfall/stream going can be a chore to keep the ice dams broken up to keep the water flowing INSIDE the pond/stream etc. Use your heater and keep a bubbler pump going to keep a hole in the ice if you shut the falls down. You really don't need a heater as long as you keep a hole in the ice for the gases to exhange etc. Stop feeding your fish when you get in the 50 degree water temprature, but they'll stop on thier own anyway.
St.louis Ponds and Waterfalls
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