Algae ID, please? White fuzz/fine hair like algae on live rock

[JuliaRuss]

Hi! A newbie hobbyist here. These white, fuzz/fine hair like algae appeared practically overnight on my rocks. Would appreciate some help IDing it. The tank (Fluval Evo 13.5G) finished cycling three months ago.

current live stock:
A RBTA
A zoa frag
An emerald crab
A peppermint shrimp
2 Mexican turbo snails

water parameter:

salinity: 1.025
Temp: 76F
pH: 8.3
NH3: 0
NO2: 0
NO3: 0
Mg: 1200
Ca: 280
PO4: 0
Kh: 150

I know calcium and magnesium are on the lower end. I am addressing these issues now.

Thank you so much for the help identifying this algae!

 

[arussellnsg]

Looks like the start of GHA. Green hair algae

 

[JuliaRuss]

Thank you for your reply! I have green hair algae too...at the lower rocks. So when GHA first appears, it’s white? Sorry this is probably a really silly question....

 

[arussellnsg]

Mine certainly did. And it turned white as it was being "beat out if nutrients" if you will, by live phytoplankton and other good bacteria.

 

[DrZoidburg]

Could be hydroids, hard to tell. Any GhA I've had started green. Dead Gha is white looking though. Can only zoom in so much.