There are really 3 ways to get scratches.
1.Novus
2.Sandpaper then buffer
2.Sandpaper then micromesh (or just sandpaper)
All of them are just really sandpaper. The novus is just really fine liquid sandpaper thats why it doesn't work for deeper scratches. If you started with sandpaper first then went to novus it could work. When you use the buffer you sand first then buff which is just soft/liquid sandpaper that you use with a buffing wheel. But buffing introduces heat if your not careful which can lead to crazing. The best is micromesh but with all these methods the first sandpaper you use will do 70% of the work. Thats why the first sandpaper has to be coarse enough to get the scratch fully out. Then u work up thru the finer sandpapers. If you skip a series like going from 400grit to 800grit you just have to do more work and use up more sandpaper. So the easiest way is to really just go thru the series. I can tell you from experience that its a lot of work.
The problem with doing any of this is you change the thickness of the sheet in the area you sanded. So it will be clear when you look straight thru it but when you go to the side it gets distorted. Its better when there's water in the tank but still noticeable. Depending on the size of the side with the scratches and how bad they were it might just be easier to sand the entire surface.
Wolverine57, like others have said its probably easier for you to just wash it and leave it alone.
Mike - Hey Mike, how you been? I'd like to help you with that, I'll send you a pm later.