Help ID'g this algae

[92reefer]

My tank is now 3 months old and I've had this nuisance algae appear (mostly on the sand) at about the 2 month mark.

I didn't want it to get on the rocks and spread throughout the tank so I've been keeping alternating a few days no lights and then short photo period of about 3 hours for the past 4 weeks.

It hasn't grown tremendously except for a few new sprouts here and there, but it's also not declining or going away. There isn't any bubbling whatsoever in any of the patches so I'm really hoping it's not Dinos.

I'm been doing FO tank like this in the past and have never had any problems keeping the sand and rocks clear and algae free. I control feeding and photo period as well as using Vibrant on maintenance doses but Vibrant hasn't appeared to do anything on this stuff in this new tank.

There are 2 yellow tail damsels in the tank eating well etc. Any suggestions for getting rid of this stuff or at least identify what I'm dealing with?