I agree with both Motley and Larry
Carbon and more frequent water changes may be in order.
A smaller (under 125g) mixed reef tank can be challenging. I my self have mostly softer corals (zoas, Acans, mushrooms, hammer\frogspawn) and have learned that when I started adding a limited number of SPS (green slimmer,various Monties ect) I had to increase my carbon filtration. I already do 20% weekly to bi-weekly water change. I realize that this is easier for me than others on the board due to the fact that I only have a 37g display\20g plumbed-in grow-out tank\15g sump. Not a large water volume to change out on this schedule.
I also think I skim big time for my little system. I use a coralife Super Skimmer 220 (LOVE this thing).
All that I am saying is I think as newbie reefers (Including myself here
) "WE WANT IT ALL"
. I am always trying to mix species in my tank that don't even come close to inhabiting the same eco niche in the oceans...and I'm trying to make them live together in a water volume of roughly 72g
I am now trying the adage of "Less is More".. not always successful but I'm trying
I also research like crazy, anything I want to add to the tank. I've had to change my thinking and give up ideas on keeping some specimens, but its for the best, I think, in the long run.