Karin, I think most of the problems with Calcium Chloride date back to before we started using 2 part buffering systems. I used Kent Turbo Calcium in the 90's and it was a constant chase to keep the alk up since ca. chloride depleted it so rapidly. Kalkwasser was a better choice back then.
The main negative side effect I saw from using turbo calcium was that impellers and other mech parts seemed to get clogged up with calcium crud really fast.
And yeah, Hiatt kept recommending those blocks but I never used them.
I refuse to join any club that would have me as a member.
Groucho Marx