Algae Problem and more

[greenchrom]

I have had this ongoing battle for a while now with a surface algae. I have a 29 bow front tank with high flow throughout and the surface as well.
Ammon 0
Nitrate 0
Nitrite 0
Im not using tap water and the reef is over 4 years old.
about 4 months ago I got this algae that sits on top and no matter HOW much flow i put on this sucker it comes back. its sort of a thick film/ brown green in color and has an odor. its thick enough that when i reach in my tank it leaves a film of brown on my arms etc.
Ideas on how to beat it/ get rid of it?

 

[earlybird]

Do you have a skimmer? Sump? What kind, if any, of mechanical filtration do you have? I would think that a skimmer would do the job, definitely a sump would.