I am not an algae expert but posting pics or contacting reefcleaners may helhelp with an ID. The 0 nutrients is the dead giveaway that makes me assume dinos. I do think algae problems often involve species and it's not often you have a single type of algae causing problems.
I was battling something sounding similar recently. What I did was scrub the rocks with a toothbrush to try and get it off and stir up denitris every other day, then do a 20% wc snd clean out the filters. Didnt seem to get me far so I beefed up my cuc with lots of trochus and ceriths and added some conchs and start h2o2 dosing. After it seemed to wind down I did a 3 day blackout to knock it out. I also took the reds and greens out of my kessils. I did not lower my feeding in this time and and feel like I'm finally to where I want to be. Hard work with lots of scrubbing and staying on top of it the past month. Every time I walked by the tank I'd see another tuft and whip out the toothbrush. I'm going to continue dosing h2o2 but cut it back to once a day instead of twice. Helps my ph stay up and decreasing the need to clean the glass. No I'll effects on corals or inverts