I’m no algae expert but it looks like either diatoms or dinos. If they disappear at night, then they are dinos. If not then they likely are diatoms. If it’s a young system there’s a higher chance it diatoms. If it’s an uln system then it’s likely Dinos as they enjoy extremely low nutrient tanks. Diatoms are pretty simple, keep nitrates about 5-12 and phos about .05-.15 ish (this is my personal preference of course) If it’s Dino’s then you should increase nitrates and phos, try to aim around the range that I’ve already given.
Also lowering light intensity works as well as decreasing the amount of hours the lights are on for
(This applies to most algae if not all I believe)