Tank design and glass thickness q

[Borre]

Tempered glass is heat treated after cutting or drilling and can not be altered.
Any attempt to cut or drill and it will shatter.

Okay! Thanks! Is there any way of telling if it is tempered?

 

[Pharaoh]

You can use a polarizing lens to see the tiny little stress cracks created from the tempering process.

 

[Borre]

You can use a polarizing lens to see the tiny little stress cracks created from the tempering process.

Thanks! Good to know what to look for. I'd be guessing that refractional properties are nothing to go by, that if there was a difference that it would be too minute to actually make out as I'd not expect tempered glass to be much denser than normal glass. However I'll give that a try too, just out of curiosity, I have a hand held laser and could see if the angle of refraction changes between panes. Not sure if that'd tell me much but, trying doesn't cost much.