Use a pond aerator as a choice to oxygenate your pond. Proper aeration is vital to having a healthy pond, water garden or lake no matter what time of year it is.
Use a pond aerator during hot weather to provide the necessary oxygen within the pond.
Use a pond aerator during the winter to not only provide oxygen to the pond (and fish within it) but to also provide water movement at the surface to keep an area of the top of the pond from freezing.
This opening in the ice allows for fresh oxygen to enter and an exit hole for toxic gases from decomposing organic matter in the pond to escape.