Drilling tanks: compromising integrity?

[in2deep]

Just got a new 30 tall and would like to drill it near the top of the rear pane for an overflow. If the tank doesn't crack when it's drilled is there any known compromise of the integrity (CRACKING) of the tank vs. an undrilled tank? My paranoid mind is saying that it must enhance the odds of a pane failure but lots of tanks at the LFS are drilled.
Thanks

 

[AquaReeferMan]

As long as you have a bulkhead on it, it will be fine. I have a 20 long drilled in each corner for my fuge. Its been drilled with water in it for almost 2 years now. Ive seen custom tanks at work that look like swiss cheese and they work out fine.

 

[Roy G. Biv]

I have 6 - 20g and 5 - 10g drilled in the top corner for a 2 1/2" bulk head each. 1-20, and 1-10 have cracked by the bulkhead. However the bulkhead keeps the glass from moving. I used a little silicone along the crank and all is well, so far