Eep! I just had mine id'd as cyanobacteria/GBA. It hasn't gone very far yet, but I have a feeling it's going to spread if I don't do something.
I'm planning to cut the photoperiod to 6 hours, perhaps raise the lights some, and clean the tank thoroughly as I do 50% water changes twice a week.
Sorry you've got it too. Now I can truly sympathize.
Any other pointers about CB (cyanobacteria) will be well appreciated. Thanks in advance.