sounds like you're putting in one of those AquaScape-type underfiltered, rock and plant infested, insufficiently deep water features that are guaranteed to kill koi even in temperate zones.
You're in Canada, dude, and koi are not cold water fish -- so buy the cheap, disposable kind, 'cause those that don't immediately succumb to pathogens, parasites and predators will turn into koisicles come winter.
Thought we'd covered all those bases last time you showed up here?
Here's the URL for North American Water Garden Society:
http://www.nawgs.com/
Maybe they can help with what you've got in mind?