ID please

[osmaven]

Can you please let me know what is this red stuff (cotton like), and tell me if is bad for my tank. Also if it is, how can fight it with no chemicals.

 

[D659600]

Cyano bacteria. Chemi-clean or Red Slime Remover will get rid of it for now.

 

[graveyardworm]

I dont think its cyano. Check this thread Nightmare red cotton algae . Its a long read but the info should help.

 

[graveyardworm]

Asparagopsis is the name. Check this link. http://www.marineland.com/seascope/ss2003_issue3.pdf