http://reefkeeping.com/issues/2003-03/rs/feature/index.htm
I got directed to this page/site after looking online at some vendor and checking out their salt, they had started to carry some different products after reading this. Now, I've seen a blurb elsewhere about this study, saying it wasn't in depth enough, and that some of the manufacturers have changed their compositions. I don't really know, it was just food for thought and I got interested in "real people" experiences on the subject.
IME, which, admittedly, is almost 10 years outdated, IO was a bummer, I had problems with calcium levels and keeping steady
ph on it, and I had switched to Red Sea and still wasn't happy with that. In my area it's either Red Sea or Instant Ocean, there really isn't much variety here. The
LFS all use Red Sea here, and also all use the local city water. The combination seems to do okay, I've seen a lot of local set ups they've done in offices, etc, and they look good. But I've heard terrible things about Red Sea, and I've got my own old experiences with it sucking. However, mail ordering salt just seems to be kinda odd to me.