You can still use windex...just don't spray the glass directly...spray the paper towel away from the tank instead. Or else, you can use vinegar (which is a little safer) to clean the glass.
I just use one of those towel thingy things, now to get my translator out to tell ya what they are called! :roll:
Its like a shamwow....... but its not.... jeez all day imma be trying to think what its called!