Resealing an aquarium?

[Oliverian]

Ok, so I have a 45 gallon long that has rats in it right now. It hasn't been used for water in a while. The rats have been chewing on the sealant in the corners a bit, and I was wondering if I could ever use it for fish again. The rats are moving to a big wooden cage once it's done, and I wanted to set up the tank again with fish. How should I go about resealing it?

Should it be cleaned with anything special beforehand, like alchohol or something? I don't want anything that might corrode the sealant or weaken it somehow. And is the stuff they sell in the pet store, aquarium sealant, is that any good? Or are there other sealants that work just as well that are cheaper? (the specialised aquarium stuff usually costs more) I heard you can use food grade sealant, but I wasn't sure.

Sorry for so many questions! I'd really like to get this tank up and running, because i'm deprived of fish with my little ten gallon right now.

-TammyR (and yes, I did ask on AllThingsAquatic, but wanted to ask here also)