in my short time as an aquarium hobbiest i have noticed that most tanks are constructed out of plain old annealed [plate glass]. why not use tempered or even heat strengthed glass. tempered glass is 5 to 7 times stronger than plate and i believe that heat strengthened is about 3 times stronger. tempered and heat strengthened cannot be drilled after it is tempered, and is a little more expensive. other than those two reasons does anybody know why. i dont think there is a fish in the world that could break through a piece of 1/2 or 5/8 temp glass. with all these monster fish why not use stronger glass.....