yes iron is sometimes to hair algae related IME.
i had a very iron rich flourite before the tank redo, and dosed a lot of flourish and flourish iron, and didnt keep up with water changes, and BAM!
i lowered iron dosing and it went away.
but now, it was just NTS. i got 4 amanos, 2 young SAE, and started my EI autodosing on sunday. i did not see the tank monday or tuesday, i came yesterday and there was not a scrap of algae in the whole tank.
i just hope it doesnt come back.