Fish Guy

I have algea that is blue-green in color, but it isn't slimy or it doesn't grow in sheets. The algea grows in circles on the glass, but after I scrap off the algea it doesn't come back as fast as blue-green algea is often described.

enthusiast

the circular-growing algae is cynobacteria i think is what its called. there is also a blue-green algae that gets its name just for its look. The circular-growing algae usually only occurs in new tanks though? is your tank new? if not you should consider that its time for an algae-eating fish to help keep your algae in check