Image is quite blue but appears to be a combination of green hair and turf algae.
Best plan of attack is to pull off what you can by hand and then scrub rest of it off with a toothbrush, net suspended matter then do a good siphoning.
after reduce white light intensity and add some snails such as:
Turbo grazer
Astrea
Cerith
Trochus
AND A PIN CUSHION URCHIN
Hi, thanks for the ID. The tank is near a window but no natural light comes thru. I think what caused the algae was me dosing trace elements and maybe the algae took a foot given access nutrients. My nitrate and phosphat are in range NO3 2ppm and po4 0.03.
Some trace elements contain too much Fe and I've found them to fuel algae, cyano, diatoms and dinos.
I've stuck with bi-monthly WCs and daily dosing/maintaining NO3 and PO4