Chemipure is a very good addition, especially if space is limited. I have been using their products since the 80's!! I still use them on my smaller systems. I wish I had an answer for your coral loss, sometimes it can be nearly impossible to pinpoint, especially when you haven't changed anything, other than adding the corals. I like to QT my corals first and I also drip acclimate, slowly. Hang in there!!
Regarding ChemiPure, have you had any issues with Iron or Aluminum levels? I recently had a Triton test done on my water and it showed elevated levels of those two. Randy Holmes suspects that it might be related to either the ChemiPure or Phosguard that I was using at the time.