Help identifying this Algae?

[jmgre1991]

Good day reefers.
I have this brown (under blue light) greenish (under white) algae that is growing in my tank, particularly under my rockscape and on my power heads.
I dont think it is Algae, but thats why I am here asking.
My params are stable (although my PO4 dropped from 0.3 to unreadable this week with the Hannah checker low range HI713)
The params are:
- SAL: 35.6 (got a little high at 36.5 brought down to 35.5 and will drop again next week with water changes)
- PH: 8.3-8.5
- Nitrate (NO3): 11.7
- PO4: 0
- Alk: 9.07
- CA: 409
- MG: 1461
This week I stopped with dosing NOPOX as PO4 hit 0 and its not doing anything for Nitrate control I found
I do dose the red sea 4 part starting last week (after Algae flaired up)
I also dose Red Sea Reef Energy AB+, but the Algae was in full swing before I started
Some info about the nuisance:
- stringy with bubbles on and particularly under rocks (less on the live rocks vs marco rockscape)
- perhaps a different more hair like one on back wall and flow pumps
- browner more dusty one on glass which requires me to scrape the glass every 2nd day.
I do have a UV steriliser connected to my return for a few months now, does a good job at keeping the water clear
I also have a Tunze Algae reactor with Cheto, but that has not done anything in the past 2 months I've had it.
I have been adding Fauna Marin Bacto Reef Therapy and Fauna Marin Bacto Reef Blend once per week to promote healthy bacteria.
Got about 6-7 Asterea snails (adding 5 more in the next day or so) and a pair of Turbo snails
I also do a monthly ICP test, which the result you can find here https://www.triton-lab.de/en/showroom/icp-oes/202165

Overall I am not majorly concerned, I dont mind cleaning my glass and scrubbing the power heads every so often, but really curious what I am dealing with and maybe if there is a way to make life easier then do that thing.

 

[KrisReef]

Looks like good old green hair, but it's not all that clear in the pictures.