Outdoor Pond --- what to do with my KOI???

[Perodogo]

Hello everyone. This may sound silly but I'm just wondering if there are any reefers out there who also have outdoor ponds?? I've been stressing about what to do with my KOI's now that winter is approaching. Has anyone left theirs outside all winter? If so, what type of heater/deicer did you use? How deep does your pond have to be for the fish to survive our harsh Canadian winter? Or would you advocate bringing the fish indoors (which I'm not too crazy about since I really don't have the space for another aquarium)?

My pond is about 1000+ gallons - approximately 24 inches deep and most of my fish are 4" - 8" (although my biggest one is about 10").

Any advice is appreciated.

Cheers