Algae ID?

[SourAngelfish]

Ok, I have a lot of questions. My tank is going through that faze where all of the algae goes through. I have only base rock so I didn't start with liverock (I don't like the critters). I need help identifying which algae types are good and which are bad. First of all I have these black algae like specks on my rock, some are also on my glass too; my astrea seems to eat them but the conch won't. Second is the red algae, I think it may be coralline as there was some reddish purple coralline on my astrea's shell. It was also encrusting the rock rather then clumping. Third are the two types of green algae. There was a little bit of hair algae but I cleaned that up, but there is some green algae that is encrusting on the rocks just like the red algae (coralline?). I'm mainly concerned about the black spots though.

 

[Jisko]

any pictures? detritus build up and such can appear black and almost like a weird dust but if its sticking to the glass i doubt thats what it is :\

side note black algae I believe its from a lack of oxygen in that spot on the rocks