I use Pro-Mix BX for most of my potted plants, including several cannas. It is very good stuff. This particular mix does not contain any fertilizer so you can add the fertilizer of your choice.

Regards,

Rokal

I am looking to mix my own in bulk to cut down on cost. I have a lot of very large pots to fill for about 30+ different canna.

I am looking at a maunre, peat moss and pine fines mix. Given once they leaf out they will be in standing water I only need a rich medium for support and food.
Any thoughts?

In MI, I would recommend adding some sand to a promix type base. Your cannas will not grow fast for as long as southern climate cannas, and will need better drainage. I have not tried it, but if wanting to stay "lightweight" perlite should give similar drainage.
Also, in pots remember to fertilize often as the roots will not be able to pull nutrients from the soil as in ground cannas do.