Drilling a aquarium

[crazywesc]

I have a marineland 120gal tank I need to drill and put a overflow in. But I'm not sure if the glass is tempered or not. I bought it from petsmart and nobody there could tell me if it is or not. So is there a way I can tell if it is tempered?

[der_wille_zur_macht]

Contact the manufacturer.

Also, looking at the glass with a pair of polarized camera filters will reveal a telltale pattern if the glass is tempered. It's tricky though, and kind of hard to explain - maybe search on here? I wouldn't be surprised if it has been explained in the DIY forum or elsewhere.