In my pond I use an aerator from DIY Pond Aeration and I believe it is 1/4 HP. It runs 2 diffusers. The diffusers are made of soaker hose made into a circle. The first one is about 30' form the compressor and the second is about 100'. It was always my contention that fish needed the oxygen in the winter to survive. The first year I filled my pond, 2016, with well water and stocked it and I lost all of my fish b/c of no oxygen. I think because it was well water there was no oxygen in the water when I pumped it into my pond. Ever since I have ran my aerators 24/7/365 and this will be the 3rd winter. So I had one winter w/o one and one winter with the aerator and I haven't lost any fish. At least none float on the water. I was told that if a fish dies in the winter it will float to the bottom. Also, the rep at DIY told me that it was best to run it year round. I live in NW KS and our winters can be cold and the pond will completely freeze over. Electricity cost is not an issue, it doesn't use that much. It seems that everyone who does use an aerator on this forum uses them sparingly.