Is this the start of coralline algae? I am in the middle of a dino and cyano battle and noticed these green circles have started popping up on my rock.
IT could be, but hard to tell. Do you have anything in your tank that already has coralline on it? A rock? or snail shell? Did you use the bottled stuff? I ask because coralline does not just eventually appear in a tank, it MUST be introduced into the tank on something.
I do but its purple. Most of my snail shells and frags have it on them and when i first started the tank i scraped some of the shells to try and introduce it. I just want to make sure it is hopefully something positive to offset all the other stuff.