Chris - In my experience sarcophytons , nepthea and colt corals are some of the worst for chemical warfare but there are others I'm sure.

Manny - I run carbon for about 3weeks out of every month. Some run less, some 24x7. I recently took most of the soft corals out of my large tank so we shall see if it helps growth.

Not to make it sound like you can't mix them just that many of the compounds released by softies (google terpenes for one) will seriously stunt their growth.