Hair algae good or bad

[newtomarine]

 

[Alanc425]

Good if you're approaching the "end" of your cycle or a new tank. Bad if this is an established tank

Try some turbo and trochus snails

 

[Diesel]

I would say bad either way as I prefer diatoms above HA as HA is a pain to get rid off.
Remove it manually.
In that way you still can finish your cycle before you start to fool around with your nutrients.