I have a Mini-L and a 2211. I think an adapter would be a poor choice.
I have this for outflow
and this for inlet
They're perfectly sized for the tubing and they provide the perfect flow for the tank-- not too strong, but they circulate water well over every cubic inch of the tank. If yo use an adapter to connect a larger 13mm outflow, you'll have much less of a stream coming out, though that may be what you want with a smaller tank. If it's anything larger than the Mini-S though, I would strongly advise against it. If you're using it on your 12long, I don't think this filter is going to do it for you-- there's been too many people who have reported having stagnant water on the opposite end of the tank, some even with a 2213 (unless they're using a spraybar across the *entire* tank).
Moral of the story: the larger a piece that you put on the end of the outflow, the less flow you're going to have. Stick with a small 9 or 10mm piece.