herzausstahl
Chumono
So for ponders in cold climates like mine you get a few different takes on overwintering...run an airstone to keep a hole in the ice for air exchange (people worry about toxic gases building up, I always figure bacteria slow down in the cold, not a huge issue), run a heater to keep a hole open (done this with a 100 watt one that will open a small hole, some use 1500 watt farm trough heaters), pond breathers (lower watt that have long breath tubes to keep a hole open,there's a guy zone 2-3 in canada using these with success, ones like me running a pump with a hose pointed at the surface to keep water moving, I've done this with great success, only lost big fish when I undersized this as my usual one failed early winter & I was ignorant as my fish load was too high at the time. So I run a pump rated to cycle the pond an hr (gph on pump equals pond volume, recommended cycle half the volume an hr normally). So each spring I switch over to my summer pumps. I have one to run a waterfall that used to be connected to a pressurized up filter (filters in the pond world equals soil wars in bonsai). The first one I started up is this one. Now it just runs a waterfall and directs some water into the first bog I made. Looks like the videos are too big to load from my iPad so I'll work on that & get them up. When I start up the stream is the coolest one.