Any idea what kind algae is that?

[Riga]

 

[leepink23]

Looks like hair algae to me

 

[Jono1487]

Agreed on hair algae. Your best bet is to remove as much of it by hand as you can. A toothbrush, obviously one that is new, is your best bet to get it off rocks. That or siphon the sand.

 

[Goodair]

Looks like patches of GHA, remove them and try not to let any strands float off.

 

[Riga]

Agreed on hair algae. Your best bet is to remove as much of it by hand as you can. A toothbrush, obviously one that is new, is your best bet to get it off rocks. That or siphon the sand.

Thanks.

 

[vetteguy53081]

Green hair algae. Temporarily reduce white brightness and remove as much as you can by hand,
Doribella sea hare or small urchin should mow this down for you