So I did the LCD screen/polarized sunglasses test on a 29 gallon tank I got from a friend, and the glasses blacked out. From what I've seen on youtube, black means regular glass. During drilling, the glass popped. Afterwards, we destroyed the whole thing and found the front/back were tempered and the sides were just glass. Is there a better way to tell if its tempered, now that I have to start spending money on tanks?