I've found the magic scrubby eraser sponge to be my go to keep my tank sparkly clean. It works great on acylic and glass tanks. You can rubberband one to scrapper with handle to get to those hard to reach places.
http://www.spongeoutlet.com/store/home.php?cat=11
What's yours ?
http://www.spongeoutlet.com/store/home.php?cat=11
What's yours ?