2ppm in the RODI
is not so bad.
Algae management is done by nutrients control. You're probably using cheap API test or another cheap branded NO3
tests. My API test always show both 0 for NO3
. Maybe you want to invest in a better tests kits like Red Sea.
Anyways, the treatement is the same for any readings you'll get, nutrients control. I will say try to see if you have dead spots (no waterflow) in your tank and remove the gunk that accumulated at thoses places. Check your sump and remove debris, clean filters pads (or bags), clean everything. Once this is done, this will release bad nitrates and phosphates in the water, so make a bigger water change after you done this. IMO
you can rebuild your reefscape, it will release a lot of nutrients in the water too. You can stirr the sand a bit to remove gunk of it...
The algae you're getting look like hair algae, it's because of high lights + nitrogen (and phosphates). If you have ammonia/nitrites in the tank because of a mini-cycle, it feed more this algae than nitrates.
What's your waterchanging schedule ? You can help with toothbrush cleaning affected areas.