You are certified for Canadian waters, but I really suggest you do a one-day course with a Canadian instructor, if you haven't used all the cold-water gear. I'm sure you'll figure it all out on your own, as it's mainly just more warm stuff, rather than any other technical gear, but I've already seen tropics-certified divers get a little freaked out using all the gear they required off the west coast of Canada. (It might not be as freaky in an Ontario lake, though.) Fun hobby, though, eh? It's addictive.