I drilled my first tank a couple of months ago under supervision of someone more experienced. It was far less drama than I expected. This was a 125, so we didn't build dams or anything like that. Just ran a garden hose slowly on the area being drilled. Let the drill do the work and grind your way through the glass. I used a cheap bit from Jason and even traded it back to him when I was finished. Next one I won't be so nervous.