Would love to see pictures of your homemade pond “greenhouse”. I’m also a northern WI ponder (Shell Lake, WI) facing my first winter with koi. I’ve already been researching the best way to overwinter my koi. I want to avoid bringing them indoors if I can simply because I’m such an animal lover, it would break my heart to coop them all up in a 300 gallon tank all winter…especially when the water temps would be warm enough indoors that they would remain active.