Drilling 125 gal tank?

[Leo73173]

I have recently came across a 125 or 130 not sure. It is 6' long 2' tall and 18" deep I think. Anyways a want to put a center overflow in it. My first question is how do I know if it is tempered glass on the bottom before I drill or have someone drill it for me. Next question is what size holes should I drill in the tank if it is possible. Any help would be great. Right now I have a 55 gal with a refuge/sump. Thats has an overflow filter box and u-tube. I dont want to have that with a tank twice the size....Im sure you all understand. Thanks in advance for any help

 

[fat-tony]

the bottom most definately will be tempered. As far as drilling, decide what you want for flow with the calculator and the drill for that bulkhead size

 

[Jeremy Blaze]

I agree, the bottom will definatly be tempered. Sides are probably not.