I would say right off the bat, less light. As much as your corals can take. And you may need to turkey baster some of that out manually. That is out of control. I was just on your other thread about a fish you wanted to get and now you're saying you're going to get a mandarin. Those a delicate creatures. IMO, Keep your head off of stocking and keep focused on the problem you have going on here. Once you get this taken care of, then stocking. Now... That being said:
I would try a but more flow. I would go to an LFS that sells Chemipure, and are you using tap water? If so. Stop it. I don't know that you should be adding any more creatures right now, like hermits or anything... That's just what I would do. Try sucking it out and a gravel vac or a turkey baster.