Aquaforest Reef Salt - arrived as a 10kg BRICK

[ReefGrrl]

Has this happened to anyone else? After reading many positive reviews, decided to get some. I got the bucket yesterday from Amazon, 10kg (want to start phasing from H2Ocean, so hoping to start mixing the two).

But it has solidified into a big solid mass! When I opened the bag I was happy to see a measuring cup in there but when I reached in to get it, I couldn't pull it out. Then I got my big spoon to move some salt away - only to find that it is a solid mass. I managed to break off some chunks and I hoped it was just a crust, but nope: it's solid down at least two inches, which is as far as I could get. And the chunks aren't falling apart: they are solid too.

I know salt mix settles in shipping and should be stirred well before using, but to become solid like this - ?? I don't have confidence that it's properly mixed, nor do I know if I can even mix it.

Is this common? Should I just return it and exchange for another one?

Or is there something I can do with it to make it usable?

Thanks for any suggestions. (Shaking head at this...)
Cindy