drilling tank glass

how can you tell if your tank bottom is tempered or not? if it is tempered,would drilling the back close to the bottom acceptable or work just as good for over flow. are standpipes really needed? i'm not familiar with reefready tanks....i'm currently using a overflow box.
i might be getting a 50 gal glass tank soon (non drilled ) and i thought i would try drilling it and make it so called reefready
when tanks are tempered, i'm thinking it is only the bottom....am i correct about that?

 

So few tanks where ever made with non tempered bottoms I never take a chance I always only drill a vertical panel myself ..

 

I suggest calling the company who made your tank to verify. Some of the cheaper tanks use tempered glass all the way around (such is the case with mine), for whatever reason.

 

Won't work ! I called Perfecto several yrs ago a 40 gal flat back hex.. Lady said nope not tempererd at all bottom sides nothing tempered.. I said well I doubt the bottom is not tempered ! I set up the drill press got tank set up to drill then said ?? let me call the place again maybe I'll get someone else ? Wrong I by chance got the very same lady I said hey Its me again just have a funny feeling about the glass and wanted to double check she said no sir drill away! I hit Play on the drill motor ! and was talking to her still when she asked what was that bang ?? Scared the hell out of me like 12ga point blank LOL the non tempered tank i said Thanks LOL she said have a nice day and hung up ..That other new hex tank flooded over the HOB overflow several times before I retired it ..

 

Great, leave it to customer service to leave you with more questions than when you started. I actually took my tank to the glass shop next to my transmission shop to be drilled, and discovered it was all tempered that way, so luckily nothing was damaged/ruined.