It's funny, it started (atleast to a noticable amount) in my main tank, ok not so funny but it first showed up when I switched from bluer bulbs (14kK) to more yellower (10kK). I have started seeing it growing on rocks & acrylic in the refugium (nothing in the sump though, only ambient light gets there though). Also the other tank that i have linked to the system is just now starting to show signs.. so I'm going to suck out as much as possible, do a big water change and then see where I am next week. Also swing on over and get another pH test kit, another brand.
I've basically cut back a lot from my corals. Moved all my zoanthids & sps/lps frags to a separate tank that has zero fish in it (a grow out tank if you will). So not a large issue of cyano over running corals. I have an open brain, large toadstool leather, a few other leathers, and some colt (other than some zoos & mushrooms that were attached to large rocks).
I think one of my issues is that many of my detritus eaters have died off over the past year and a half. I don't see hermits running around the tank anymore, and there's not a terribly large amount of snails either. Of course unsure which snails would be useful for taking care of detritus, everytime I hear of one that is good, end up finding out they're a colder water species.