[Myka]

Looks more like bacteria than algae to me...possibly a dinoflagellate. Does it stick to the rocks real good or does it come off easily? It it's stuck on there well then I'm wrong - dinos and bacteria will peel off easily. If it's stuck on there then looks like maybe a brown turf algae.

Essentially they are all treated the same (some particulars) - a person has to lower nutrients in the tank. Watch maintenance, look for settling detritus behind the rocks, start siphoning it a couple times per week or at least during weekly water changes. You can siphon sand too. A GFO reactor comes in real handy. Be sure to not over-feed. Feed pellets only if you can. Employ a good quality over-sized skimmer. ETC.