tank drilling

You can invest in the diamond hole saw blade and do the easily yourself or you can spend about the same and have a local shop do it for you.  If you carefully explain what you need the tank to do they can set you up and if they break it.....  Another nice thing is that they can install the overflow for you.  I know Eric at Aquarium Creations does this work. 

I've had two done and it's nice to let someone else sweat about it.  Your call.

I understand glass holes web site has them for mail order, someone said harbor freight also had them.  They come metric so you need to determine the size hole you need then convert. Also the bulkheads for schedule 40 and schedule 80 are (can be) different sizes so you should consider that when you cut your holes. 

Have fun and let us know what you decide and how it works out.

Fat

I have drilled Aquariums in place before.