Well I had about two inches of fine CC when I started the tank. I am running all filtration through a bed of macro algae(ecosystem with mircle mud) at 2000 gph. No skimmer. I was experiencing constant diatom outbreaks and unsightly algae. The marco in the refugium wasn't taking off like the literature says(all the stories of trimming out handfuls of macro each month). Couldn't get control of things. Went to a LFS where I was introed to a couple of reef systems without substrate. They were very clean looking and no algae problems. So what the heck, I started doing 20g water changes sucking out the CC. It took three changes over a month to slowely remove most of it. Immediately the algae went away, but the most promising change was the macro. It started growing in thick masses. To the point where I had no water movement across the top due to the macro getting so thick. Thick algae started growing on top of this bed also. The display looked great. I still have detrius at the bottom of the tank in areas of low flow. I will be addressing this soon with a closed loop system with a squid attached. Idea is to set up current to push all detrius to the back of the tank where is can be easly sucked out with 5 g changes each month. I am experencing another algae outbreak currently but I attribute this to changing the light schedule and adding another VHO(changed rock work also). Now running 3 VHO's, two super antic, one antic with 2 400w MH 20K's. Aside from a melting colt, my tank has never looked better.