Firstly you need to know what glass you must and must not buy. Yes there are different types and not all glass is the same. Tempered glass should never be used, it is not strong enough, especially if you intend keeping fish and you will be filling the tank with water. You should speak to the supplier, as you are looking for plate or sheet glass, which is considerably stronger. In addition to this, the glass will break into larger pieces if broken, which can be beneficial when it comes to cleaning up along with keep you and your family safe.