@RealtyBoss if you really want to know what your dealing with send a sample off to @twilliard.
He got a great scope and will determine what you dealing with.
Following along also. I have some slimy grayish-brown snot looking stuff on my rocks in my nano. Cleaned it up a bit today and added some MB7. It is not killing any corals though. Here is a spot that I missed. Does this look anything like what you have @RealtyBoss ? Hopefully the info you get can help me out also. Been doing this for a long time and this is the first time I have run into this particular plague.