It is not possible to buff a scratch out of glass.Acrylic can be fixed,but glass can not.If the back of the tank is in better shape,you can just turn the tank around.Otherwise you either live with it,or replace the panel.
Hey,
Sure, just turn it around why didn't I think of that! Kidding!
That's what I was afraid of. I thought maybe somebody had come up with a way to do it. I bought glass instead of acrylic to cut down the chances of scratches. Oh well. I can live with it.
Thanks,
Dan'l