Removing scratches from an acrylic tank

[DarkHorseMBA]

Hello everyone,
I'm new to the group and saltwater/reef tanks. I've been keeping 2 fresh water tanks and have been waiting to get into a reef tank, mostly limited by cost. This weekend I picked up used 60 gal tank with built in wet dry filter for $100. The filter system is like that of the seaclear systems or red sea max, with the filtration built into the back of the tank. I'm not sure how all that plumbing works, but that's for another post.

The tank was a great deal, the owner just wanted it gone, but it's acrylic and has lots of scratches on it. Most of the scratches are on the inside and range from deep enough to feel with my finger nail to light, probably not visible with water in the tank. When i bought the tank the owner told me that once water was in the tank the scratches are not visible. I'd like to remove the scratches, but I'm not sure how. A google search has provided some ideas on using fine grit sand paper, but that just seems counter intuitive. Another search led to a set of creams/liquids "http://www.novuspolish.com/" to polish the scratches out.

Has anyone had experience with removing scratches or polishing an acrylic tank?
Any advice or help would be great.

Thanks,
DarkHorse

Added Some photos