If your pond is heated what temperature are you going to maintain through winter? Why have you chosen that temperature?
I am currently at 14 degrees centigrade. I am thinking of going down to 12 degrees centigrade although I worry about the view that temperatures between 10 and 14 degrees centigrade is where parasites are still active and Koi are less active with a reduced immune system.
I am down to 16 deg but will reduce slowly to 12 deg as I have for the last 3 winters and not had any problems.
I feed lightly once a day to avoid sore mouths due to fish mouthing the pond walls for food.
I’ve just brought it down very slowly to 8.5 degrees. It’s currently above that at ambient most of the time but I’m just going to leave it at that all winter. Koi are safe, they get a proper winter and it doesn’t cost me an arm and a leg!