First let me say that I am way new to this hobby and by no means an expert. I can only comment on something I've read about or experienced myself. With that disclaimer out of the way, I *think* it may be Cyanobacteria. I sent some pics of my tank to John at reef cleaners, looking for help with algae. I didn't even notice the cyano in my tank, just thought it was some nice color developing on my live rock, but John pointed it out to me. Looking at my tank tonight, I see lots more of it. Looks like someone took some reddish- pink powder and sprinkled it around.
Hope this helps, or at least gives you something to either confirm or rule out.