Cold Crashing temps

So how cold can you go with cold crashing?Suppose to get down to 25-27F tonight would that be too cold?

 

Assuming your beer is over 60F I don't think there's any chance 25F will freeze 5 gallons overnight.

Edit: I bet there's a formula to figure this out.

 

I have heard some horror stories on here about doing exactly what your talking about. The problem for the most part is using a glass carboy. The beer will freeze from the top down. When the top inch of the beer is frozen is prevents pressure from the water expanding to release through the airlock. All that pressure from the expansion will break the bottom off the carboy. It's pascals law of hydraulics in action. I'd assume it would push so hard on a bucket that it would cause a crack.

 

Chance of freezing may be slight, but with a glass carboy it still has some risk of breaking. Doesnt need to freeze solid to break it.