8 Tips for drilling holes in glass aquariums

Need to drill a hole for bulkheads in your glass aquarium? Here are eight tips that may make the job easier.

1. Practice
If you have never drilled a tank before it is highly recommended you practice on a smaller tank, one you won’t be using. Drill a few practice holes and get a feel for the process, before you drill that 250-gallon dream tank.

2. Use a veritable speed drill
Drill bits for glass use diamond partials fused to the bit. These ‘scratch’ their way through the glass gradually. Using a slow to moderate speed is more likely to result in a cleaner cut. Note: it does not matter which direction the bit rotates.

3. Drill bits for glass have a limited life
You can expect to get about 75 to 100 uses out of a reasonably priced bit for glass. A cheap bit only lasts about 10 to 12 uses. The extra money is worth it.

4. Check for tempered glass

This perhaps should be the first tip, as you cannot drill into tempered glass. It will shatter into pieces. To determine if your practice tank and the tank you intend to drill are tempered glass, you need polarized sunglasses and a laptop with an LCD screen.

Get to a white screen on your laptop and put it behind the glass. Put on the sunglasses and look through the glass at the screen. Turn the laptop like a steering wheel. The screen shifts from white to black and back to white. If you see total black on the screen, the glass is not tempered. But if the black looks streaky, or like streaks are running through it, the glass is tempered.

5. Place the cuts carefully
Cutting a glass tank can affect the integrity of the glass. The hole should be placed far enough from the edge of the pane to avoid affecting the structural integrity of the glass itself.  The diameter of the hole determines how far from the edge of the pane the hole should be.

Example: The edge of a hole that is one inch in diameter is placed at least one inch from the edge of the pane of glass – the edge of the tank.

6. Use a template

Make a simple wooden template and clamp it to the tank. This keeps the cut neat and reduces the chances of chipping.

7. Keep the bit cool

Do this with a low flow of water, a trickle, flowing over the bit. Keep the water away from the drill, and directed at the drill bit while cutting.

8. Don’t drop the puck

That circular section of glass you’re removing is going to drop away, and land on the pane of glass beneath it. Put a folded towel or thick cloth beneath the cut to catch the puck as it falls.