Are you certain this is algae? I know, dumb thing to ask, but you would be surprised.
If the tank is not cycled, try rinsing out the tank. Yeah- all of it. Clean the gravel, rinse it, rinse the plants, dividers, swish around the baffle and filter pad.
Or, try an algeacide. I dont know much about them, but from what I heard anything with polyethylene dichloride works well. Or get an algae pad and scrape it off.
How bad is it? Can we see?