Your post came too late! I dumped 8 bags of these in a few days ago, but thankfully I had no issues, and it dissolved very fast. I tend to use Diamond but I couldn't resist the ease of Wally World loading it into my car for me! Before Diamond I used salt from the pool store, and it wound up causing iron staining, so I think I'll take rocks if I have to... but warning taken, I'll stick with the Diamond kind when possible.