A buddy of mine just gave me a 90 gallon tank that his next door neighbor wanted to get rid of. It looks like the guy drained and then just put it in his garage. The inside of the glass has alot of hard water/calcium looking stains on it and ive tried everything from vinegar to clr cleaner to some citrus glass cleaner and i still cant a majority of it off. Anyone know anything else that works for projects like this. Other than these glass stains the tank is in great shape. Thanks you for any help!!!!