I got the
surface skimmer box with my Remora Pro, wich did a good job of removing that "film" on the surface of the tank. If you have or are getting one of them, you have to make sure your water levels are constant. Oddly enough, after I switched to a Reef Ready tank, I took the
surface skimmer box off.
As for the amount it pulls out...that's up to you. The higher you raise the cup, the dryer you're going to be skimming. The lower you put the cup, the wetter the skim. I skim pretty wet, so I'm usually emptying the cup at least once a day. The skimmate is pretty light in color.