How to Determine Tempered Glass


Lifetime Charter Member
Lifetime Member
Jan 24, 2005
I would like to have 2 additional holes drilled in the bottom glass of my 180 gllon tank. The tank, according to the previous owner, is an Oceanic tank, 3-4 years old, 2004-2005 vintage. It has 2 holes drilled in it at this time, approximately
2 3/8" in diameter, in each rear corner.
My problem is in determining if this bottom is tempered. Does anyone have any knowledge as to how to determine, either visually, or physically (without breaking the glass!!), whether this bottom is tempered?
I've been to the Oceanic website, and I'm waiting for a response, but would appreciate anyone's help with this problem. Thx in advance. :D