Look into "MicroMesh"...it works great(just like sandpaper), it was designed to polish aircraft windows. No chemicals whatsoever, it's all elbow grease so it's safe to do in the water with fish swimming around.
I used it to redo my 300 but it was dry at the time.
I use Novus 2 on the outside from time to time when little scratches appear. It works great for a quick outer polish.