Drilling 3mm glass (5 and 10g)

[matseski]

I would like to install 3 bulkheads on the short ends of 5 and 10 g tanks (2x 1/2" and 1x 3/4") for an auto water changer/top off system and emergency drain on a rack. I know I have seen fish rooms online that have small tanks drilled, but its hard to tell if they were reinforced. The glass thickness on the standard 5 and 10g tanks I currently own is 3mm.

The drilling should be easy as long as I keep the glass supported from the backside.

I am worried about the forces on the glass from the plumbing, particularly in case someone (likely me) bumps it. The plumbing will all be connected by hard joints, so I don't think the tank will see much torque as long as I am careful with cutting the PVC to the correct size. Bumping it worries me...

Any experiences?

 

[fishguy306]

I have heard of several small tanks cracking because the plumbing was bumped, many reef guys have run into the issue. You are right to be concerned about it.

 

[matseski]

I've seen a few people adding reinforcement panes around the holes. I'm not quite following how that helps since the whole panel will still flex and you just made your lever larger. Might do better putting the stress on uncut areas of of the glass rather than the cut edges of the hole where there are surely small cracks that will concentrate stresses.

3/32" glass is dirt cheap and will almost double the thickness. Has anyone tried doubling the thickness prior to drilling?

I think the silicone layer may ruin a diamond blade though so you may have to drill them separately and then laminate...

 

[paulW]

You can drill a 10 gallon tank. The thinner glass tanks are actually harder to drill as the whole tank has a tendency to wobble as it's drilled . So go slow, low pressure and if possible use your arm to help support the tank as you drill it (easier with a drill press). Also make sure your hole saw is sharp.

Can you put the plumbing on the back so that it faces the wall to minimize bumping? Most of my tanks are that way, the plumbing runs so that the valve to drain is in the front or side of the tank for easy access.

I have only broke one drilled tank in the way you describe, but it was due to my own stupidity.
I had the bulkhead in, was gluing in PVC, made a mistake. The glue sets in seconds, but I tried to pull it out anyhow and broke the glass. This was a 20 long. I pulled pretty hard though. I think it takes more than a simple bump to break the glass.