[Sanke56]

I also raise koi in a cold climate. We live on a little pond 80 ac and we have been skating on it for several weeks over 8 in of ice. We just came back from Seattle on the weekend I could certainly keep nice koi outside there.I bring my koi inside for the winter so the outside growing season is short. They are in 60 degree water now and I do cool them to 50 if we go away for longer times. I have wintered outside before but it is too risky. We can get 3 feet of ice on our lakes. Lots of people do winter koi in their outside ponds here they use a stock water heater and aeration usually and things do work out usually. The word I don't like is usually and it it impossible to do something if the system fails think of all that ice to move. I have been keeping koi for 20 years here maybe more.