Try to keep nephthia and leathers such as sinularia away from hard corals. Although I was told that it is best to keep hard corals and soft corals separate, a lot of people keep mixed reef successfully. I have a SPS dominated reef (but still a mixed reef) in my 120 and all of my corals grow well and have nice colors. I try not to get them too close to each other and I run GAC. I hope others will chime in about this topic so that you can get more varied opinions.
HTH,
Tomoko