Aerating your pond in the winter time is useful at keeping ice from forming at the surface. It’s crucial that fish get adequate oxygen from the atmosphere, even in colder weather, so keeping a spot of ice open is very useful.
You can use a pond heater of course, but many people also like, and might even prefer a small pond aerator to do the job. Some advantages are they can use the device year round, and they usually cost less to operate than a heater.
But there are potential challenges with them.
First, just like an electric heater, if your power goes out, you may find that your pond can freeze over pretty quickly. You can often get around this with a small generator.
The other issue we see from time to time is that ice can form in the airline and block airflow to the pond. This happens because condensation forms in the airline, and once it’s cold enough it will freeze. Initially, the problem is that you’re not getting any air or agitation into the pond, but if this goes on long enough, damage could occur in the pump itself. Usually the diaphragm will be damaged and would need to be replaced.