What do I have here...

[Flexin]

it looks different than hair algae.

 

[Dsnakes]

Looks like bryopsis.

 

[K. Steven]

I agree that it's bryopsis. You can try fluconazole, which is very effective.

 

[Reef of Fillory]

Flucanazol absolutely works on Bryopsis. If it's got a "fern" or fan-like structure, it's most likely Bryopsis




Bryopsis

From your original picture:

Edit: There's a sticky on the top of this sub-forum for Bryopsis treatment - I've also got some left over from my treatment if you'd like to give it a shot - i'm in Grand Rapids

 

[Flexin]

Will the medication affect mushrooms? I ordered some and thank you for the offer