Your pond is adorable! It is so fun, isn't it?
I'm going to toss some cold water on you, too, though and third the suggestion to return the koi. They are going to outgrow your pond in a matter of a few months - are you prepared to build that fast? We got a koi as a fingerling four years ago. She was so tiny we didn't see her for a whole year after we put her in the pond. That fish is now just as big as the biggest fish in our pond at 18 inches. Your current pond is suited for a couple of goldfish - they would be very happy to call your pond home! And when you do build your new pond, they will be ready for the move!
Welcome to the GPF - stick around and you'll see we are all friendly and love to help!