Drilling hole in tanks with water

[nochange]

Hi,

I have a 110g tall that is full. Question...has anyone drilled a hole near the top in a tank that has water in it- I mean certainly the water can be taken down a lot, but is there any reason that everything should be removed down to the bottom?

Thanks

[kcress]

General reasons would be:
1) If the glass ends up being tempered you will have a gigantic mess soon after starting.
2) If you screw up you can have a crack or breakage disaster. Having water just increases the resulting problem.

You essentially are taking a risk and can mitigate that risk by doing more preparatory work.

Mechanically you may reduce the possibility of actually cracking the glass if you relief the stresses in it before cutting it.

Example: If you have a bunch of water in the tank the glass bows. The outside surface goes into tension the inside surface goes into compression. As you start to cut the outer surface you could incite a fracture a little easier if the surface is in tension.

At the very least you should lower the water as much as is easily?

[johnrt]

There is a video on you-tube on this very subject.

In the one I saw, they were successful. . .

John T

[nochange]

I see the points on the glass stresses...good thinking and very right I'll bet!

It's not that I'm lazy but why move 100 lbs of rock, more sand, and all that water if one doesn't really need to is my take on this. I think I agree with kcress in that remove as much as possible to minimize stresses. I should have mentioned that I want to drill only one hole ( 1" dia.) near the top and on an end panel- which is not tempered. The glass on this tank has only the bottom tempered. And that is very interesting too!!! Why would they do only the bottom on some of these tanks? This is a commercial tank, not a homeby.

Will check out that video now...thanks yall!


Here's the video I seen, and must say now that I seen it...the guy has some balls! I think I'll drop the water level as far as I can! lol!
http://www.youtube.com/watch?v=OlaOl-dB ... re=related (http://www.youtube.com/watch?v=OlaOl-dBniI&feature=related)

[Rossco]

I did two 50mm(2inch) with a half full tank and it went fine. 10mm glass though.
Just remember that glass wears down the drill bit at a rapid rate and the contents should not be allowed to enter the aquaium. Easy to get around if youplan ahead.
When you start the hole you should tape a piece of plastic to the surface first. use an old ice cream lid etc. Drill through this with light pressure and it will act as a guide for the drill bit to stop it wandering on the glass. Remember that scratched glass is a big no no as it will break with very little stress along the scratch.
Also a better way of supporting the inside could be employed. You would stop alot of the splintering on the inside if you clamped a block of timber to the inside of the tank. It would also get rid of the mate holding the cup.