Help me ID this Algae please

[sderise]

This showed up a couple of months ago. I’ve been siphoning out what I can when I do water changes but it keeps coming back and seems to be getting worse. It’s attached to the sand. The only way I could get any of it off to put under the scope was to shake some sand around in a vial of RO water then scope the water. Hopefully I captured images of the right thing. Pretty sure it’s some form of algae since my yellow tang picks at it. Any help ID’ing it and how to get rid of it would be awesome.

Tank Stats
A little over 1 year old
90g w/sump, running fuge with cheato
Salinity 1.026
Alk 7.5
Calc 430
Mag 1250
Nitrate 10
Phosphate .05

 

[sderise]

Also, I tried a Chemiclean treatment thinking maybe cyano. I thought it helped at first but within a week it was back.

 

[sderise]

Bump