You may want to describe your algae a little bit. Plus provide a bit more about your tank. How old is it. What critters are in there, did you just add some stuff to your tank, etc.
I know that when I was cycling my SW tank I got what is called Diatom it kind of looked like it somebody had put a dusting of brown all over my Live Rock. If you do a google search on diatom you will get a wealth of info.
BTW I added some snails to my tank and they took care of it.