Saltwater Aquarium?

[speck-chaser]

Ive alway wanted to try a salt water aquarium, at one time, we had 5 freshwater aquariums with 3 being over 40 gallons when I was a kid. I have a spot in the top portion of a corner curio cabinet,I would like to do one in. I fount a pentagon shaped looking one that would fit perfectly with about 50 gal. The only thing that scares me was, I was reading about how the saltwater will sometimes eat up your walls and sheetrock and paint, not sure if thats true,but dont want to mess up my living room.