Can someone give me information on drilling glass.

[canadawest]

When I went to a glass shop to have my little 10gal refugium drilled they just used regular automotive antifreeze while drilling to cool the bit and provide lubrication. Seemed to work great as they never cracked my tank and like I mentioned it's a thin little 10gal.

On that note, is it possible to safely make an existing hole larger? I had a 3/4" hole drilled, not realizing that means I can only use 1/2" ID vinyl tubing to drain. I'd like to increase the hole to 1" to allow me to use 3/4" ID tubing. Anyone know a safe way to increase the hole size? :?: