Why didnt my 150G tank have anything like that on it? Its made by All Glass. Do you think someone removed the sticker or I have a different type of glass?
If you didnt have the sticker then it just means you dont have tempered glass. The major difference is you cant drill tempered glass for bulkheads. I just mention it because commonly 75 gal Aquariums have the tempered glass sticker. This would help you identify it as an aquarium instead of a critter cage.
Fish tanks are for fish, not reptiles. It is an aquarium that someone got confused with a cage. The seal might have been bad, just strip it and fix it and you will be good.