How do you tell if a tank is tempered?

[Doormatt]

*grin*

Well, either that, or try and drill it

I did some more research, and found out that tempered glass usually exhibits some polarization , so I whipped out my polarizer from my camera, and couldn't see any polarizing effects through the glass.

Also, I found this link (the post at the bottom of the page), and I tried this as well. No cross was shown, so I'm hoping neither of the sides are polarized, or it's just the bottom (which is fine). I'm just going to take it to OA, and get them to drill it (if they will), and we'll see what happens.