blue-green algea thing!

[j-j_02]

i got the blue-green algea looking spot about the size of a dime on my substrate. i was woundering if it is good or bad? please help, thank you.

 

[beth]

It may be Cyanobacteria
https://forums.saltwaterfish.com/t/73002/how-to-rid-your-tank-of-red-slime