Do you feel that you must take the algae off the sides and/or back glass or do you feel you should ?
If you feel you *must* remove it, then the best and easiest way is as Catfishmike suggested, adding some macro algae to outcompete the micro algae. Either in the main tank, or if you have fish or inverts that will eat it, in a refugium. Another tip is to reduce the amount you are feeding the fish....
If you feel that you *should* remove it, then I would have to ask why? Not only does this provide food for your snails, but as the algae releases spores, it is also feeding your featherdusters and coral. The snails will keep the algae short and trimmed, and eventually coralline algae should take it's place.