Originally Posted by BigB
I used the round type, but I purchased them from Ace Hardware. They work good. I would be cautious about using a growler as your vessel because the bottom isn't usually flat, which would make it difficult to balance your stir bar.
Just made one last night. I agree that a flask would work better, but it can be done with a growler. The key for me was to get the magnet balanced in the center of the growler when you start it up, as long as I did that it worked pretty well!