I forgot to answer your last question. Be careful with the aerator in the winter. I am in Wisconsin and learned the hard way not to leave the stone on the bottom all winter. If you overcirculate the water in the winter the bottom water gets too cold and the fish have no warm water refuge. Best bet is to suspend the air stone 1-2ft below the surface. This allows sunlight to penetrate so your pond can produce oxygen and also lets toxic gases to escape. All you need is a hole in the ice. The bottom water should not be circulated. I lost almost everything my first winter. It was a sad time.