I was speaking with one of our customers this morning. They did their own little "test" about this. Took a bucket of Magic salt and left it uncovered. Temps were in the mid teens. We then had a little snow squall that passed through. What they found was that the top "crust" froze. Their salt bin that was tarped did not freeze at all, and under the crust of their test bucket the magic salt was fine. Our truck sits outside and when I shoot the tank temperature I have seen it as low as -2 this year and now problems of liquid or salt freeze. Our pile is in a roll-off and tarped and we have had no problems whatsoever.
Remember, Magic is water soluble. if rain or snow get on your pile it will wash the magic out of the salt. At least as much as the snow hits and gets melted and creates water. The water seeps down into your pile. Now you have wet salt that will freeze. Salt loses its effectiveness as temps drop. What Magic does is allow salt to keep working to these low temps, but not if it is washed out by rain, or by snow that is melted and it gets diluted. Throw water on a salt pile that is exposed and see what happens when it is 0 degrees. All salt and agents will become diluted as they work and eventually freeze, just the way it goes.
Could snow have gotten on the pile? If it is in a bin this could happen. That is why we keep ours tarped.
delievered some Magic salt to a P&G facility here in town. I asked the P&G guys if they had any freeze up a few days ago and they said no problems. But today they called and their pile turned to bricks like mine. Now there is no way any precp got in their shed. I guess when it gets 10-20 below if there is any moisture Magic will be a problem :-(. Otherwise it works great. I still don't believe in the Caliber though.
I really don't think the Magic -0 itself is the problem. I have some salt in a barrel with so much Magic that there is Magic around and on top of the salt. The salt itself is "frozen" or clumped solid but the Magic -0 is not. I think it's a problem of the moisture content of the salt itself.
I had the same problem when I opened up my enclosed salt storage area the other day after receiving 15 yards of Magic Monday. Per the advice of a few members here, I was told to just leave it be until I needed some because the crust would actually seal and protect what was underneath. Well today I needed some. I hit it with the loader and it broke through fine but the top crust broke into huge chunks and there were some smaller chucks throughout the pile. I bucketed out two yards at a time and spread it out on the dry pavement and then backbladed the chucks and ran the loader tires over them and they busted right up no problem. In hindsight I wish I took a before and after picture. All I know is that if this was straight salt like I had last year in this kind of cold, I would still be trying to bust up those chunks.