I would agree with incredihelp on this one, the .com site will have much more competition than the .ca site, but the solution to your quandry is going to come onpage and off-page.

If you have great content, and work at creating inbound links using the keywords you are targeting you should see your rankings grow on google and likewise on yahoo and msn.

By the way, your site was not in my google.com front page results for the keyword hot tubs.

It isn't unusual for google traffic to dominate the referrals for well done sites. Google does a better job of getting rid of the spam sites.

Good luck!
<in your signature only please>