I would definitely try to save the tank. To get your hands on an acrylic tank that large is a coup, IMO
. They are not cheap, and so very much lighter than a comparable glass one. Someone will chime in, I hope, but I am sure there is an acrylic scratch remover out there for this kind of tank. I guess if it is too blurry to see the fish then it is a candidate for the dump, but I would certainly spend a little $ on a product to try to save it.
Here is a link to one product, and if you read their FAQ
section they discuss a bit about acrylic versus glass. http://www.aquariumpros.com/Merchant...roduct_Count=0