What is this algae

[Hypez]

Can anyone give me an idea on why today I got all this stringy white algae on my glass. Appeared today

Parameters are
Alk: 8.3
Mag: 1320
Cal: 430
Nitrate 2.5
Phosphate 0.03

Changed to Red Sea led 90 1 week ago using 50% white and 50% blue

Also started using phosguard in a reactor to keep phosphates in check.

Nothing has died in the tank either

 

[Hypez]

After more reading I assume this is bacterial
I did notice my tuxedo urchin spawning yesterday if that has anything to do with it or maybe it could be from the phosguard?