I have found the best way to get algae off of my willow moss is to put it in the tank with my mollies for a day or two. The mollies gorge themselves on algae (which they love) and my moss comes out looking great.
I've tried putting mine on a diet too, but they're really small for their age, so I don't want to keep them back. There's a new baby that I found, must be about 2 weeks old, so I also want enough scraps to fall to him. I think he's actually eating more algae than all the adults combined