Re: Compound Or Sandpaper ??? Fiberglass
DO NOT SAND IT!
That is only oxidation and it should come right off with some rubbing compound and a buffer.
Get a good quality buffing compund,3M makes some that can be had at any auto parts store, start with finish compound and if that doesn't do it move to a medium but go light with this so you don't burn through, it is essentially liquid sand paper.
If it is really really bad nothing more than 2000 grit wet with a sanding block then buff with the finish compound.
When you are talking paint finish even 1000 grit is pretty aggresive, we sand out clear coat with the 2000 then buff and it leaves a perfect finish.