To Drill or not to Drill

I was given a 150 gallon tank (48"X24"X30") and stand and I want to drill the bottom for a standpipe. I know that some tank manufactures use tempered glass on the bottom. I looked for a sticker, any sort of stamp or manufacturing mark in the glass, and I tried the polarized sunglass thing (even though I don't think I did it right), and I think it isn't tempered. I have no idea who made the tank or how I could find out.

So because I am not 100% if it's tempered or not what do you all think? The glass is about 7/16 to 1/2 thick and it has a faux wood plastic trim around the top and bottom. The stand says "Perfectaflo" I think this is a Petsmart brand.