Problems with Purple up hardening in the bottle
 

I bought a bottle of purple up a couple of months ago, and have been using it every day or 2 to dose calcium and it's been a great product. Sometime after Friday when I dosed the tank last and Sunday when my brother came by to check on my tank, the last of the bottle (1 inch or so) has seperated into 2 parts, a super white liquid that clouds my tank for a good 45 minutes and a 1/4 inch of hard goo in the bottom of the bottle. I didn't leave the lid off, the temperature hasn't changed at all, I didn't leave it in the sun, it didn't freeze or have anything else added to it.
Has anyone else problems like that? I searched here and reef central and couldn't find any similar experiences.

Calcium carbonate is difficult to maintain in solution, especially at near saturation levels... I had the same issue with a bottle of Liquid Reactor a while back, but you can just add RO/DI water & give it a good shake to get it back in solution...

Would it do that just overnight though?

It probably didn't happen overnight.... I never noticed mine until I got close to the bottom of the bottle...

I went to the LFS today to buy some more and he said it's fairly common if the bottle isn't shaken frequently enough and hard enough.