Need some help id algea and fixing

[xiaoyuliang]

Need some help here many thanks in advance!
My three month old 13.5 tank got those brown algae only on sand bed over the last two days. I’m not sure if it’s diatom or Dino tho. The changes are I added like 10 more new frags last Friday and changed water, vacuum sand bed on Saturday. Also cleaned the cheato in saltwater and trimmed half away.
NO3 is 6 PO4 is 0.08, KH 8.5. They were kind of stable, I dose all for reef every day.
I got hit by diatom after one and half month so I thought I’m done with the ugly phase.
Most of the corals are fine so far except the bird nest polyps is shrinking a little bit and hammer and torch seems smaller.
Is another water change necessary?
Will provide as much information as possible.

 

[bnord]

firstly - nice scape and design for a 13 - well done

What is the age post cycle and what ability do you have to drop whites out of the light for a period of time ??

 

[xiaoyuliang]

firstly - nice scape and design for a 13 - well done

What is the age post cycle and what ability do you have to drop whites out of the light for a period of time ??

Thank you! The tank is cycled at end of February so nearly three months. I was using an AI HD so it’s easy to drop white, my question is will the SPSs be affected tho?

 

[xiaoyuliang]

bump