Hello; I bought a used tank with out giving it a good look over many years ago. When I cleaned it up discovered a multitude of small scratches on all the inside surfaces of the glass. It must have been cleaned with some kind of abrasive. Look for cracks and chips on the corners if it is all glass. I have some small chips on a corner of a tank that have not caused a problem, but a crack will spread. Note - I silicone a clear plastic corner protector to my all glass tank corners now. The last i found at a local hardware store were for protecting the outside corners of wall paper. I use clear silicone to adhear it to the outside corner of the tank.
