How to Drill a Hole in a Glass Aquarium The Easy Way

How to Drill a Hole in a Glass Aquarium the Easy Way

While most fish keepers start off with easy, off-the-shelf filters from the pet store, some hobbyists want to take their aquarium filtration to the next level. By drilling a hole near the top of a fish tank and adding a bulkhead (i.e., waterproof plastic fitting that prevents the hole from leaking), aquarium water can be directly plumbed out of the tank and into a custom filtration system – like an aquarium sump, canister filter, or automatic water change system.

There are many ways to drill glass tanks. We have tried all methods and have drilled hundreds more aquariums for our fish shop and personal fish rooms. This article explains how we found the best and most reliable technique. However, drilling glass can be dangerous. Wearing safety gear is a good idea. We are not responsible for any damages, injuries, losses or damages that you might sustain while doing this DIY project. In our experience, the thicker the glass, the less likely the tank will crack. Aquariums under 40 gallons have thinner glass which tends to break between 10 and 25 percent of the times.

Materials for drilling aquariums

– Glass aquarium that is not tempered Bulkhead (slip x slip) – Diamond-tipped hole saw that matches the size of the bulkhead – Electric drill – Clamp – Pitcher or bottle of water – Flat piece of wood that is about 1-inch thick – Sharpie marker or pen – Painter’s tape – Pliers – Safety glasses – Safety gloves

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While some aquariums have tempered glass on the bottom panel, they usually use non-tempered glass for the side walls. If you want to verify that the side walls are non-tempered, you can place a phone or laptop in the tank. You will be able to see the screen through the pane. You should ensure that the screen of your device is white. While holding a pair polarized sunglasses in each hand, you can look at the screen of the device while rotating the sunglasses as though you were turning a steering column. If the glass is not tempered, the screen will look like it is shifting from white to solid black as you rotate the sunglasses. If the glass was tempered, there will be splotches or lines on the screen as the sunglasses are rotated. Look online to see video examples that demonstrate this effect.

Instructions for drilling Aquariums

1. Place the aquarium so that the tank wall will face upwards. Place the piece of wooden against the tank’s side edge. The hole saw should be placed where the bulkhead will be. The hole should be positioned low enough that the bulkhead’s drain or overflow is not below the surface of water. Also, mark the wood so you know which side of the wood is touching the rim.

1. Remove the wood from the tank. Now drill a hole in it where you have marked the dot. You should prefer to use a hole saw designed for wood. You can use the diamond-tipped saw to do the job, but the wood might smoke. The guide wood is used to keep the hole saw still in place while drilling. 2. After the guide is made, line up the piece of wood against the side edge and the rim of the tank again and clamp it down. Tape the aquarium’s interior where you can see the hole to ensure that the glass will not come out and crack the tank. The tape reduces chipping so that the hole remains clean.


1. Water should be poured into the guide hole. Some of the water will leak out so you will need to keep refilling it to keep the glass sufficiently wet. Water helps to clean away any dust and prevents the holesaw from overheating.

1. You can start the drill by pressing down on the trigger. It will begin to spin slowly, then gradually increase its speed. Use a gentle, even pressure to the hole saw and allow the drill’s weight to pull it down. Also, make sure the hole saw is level. Don’t tilt the drill or the hole might be cut unevenly. The goal is to slowly file your way through the glass, so the drilling step may take up to 5-20 minutes, depending on the thickness of your tank.

1. You can add more water to the hole saw or into the guide if the glass makes a squealing sounds. Continue drilling. 2. The frequency of the grinding sound changes indicates that the glass hole is close to or has already been broken through. There may be some slightly jagged edges on the hole, but the bulkhead’s gasket will cover them so no need to deburr the hole. Carefully pull off the tape, and do not touch the inside of the glass hole.

Diagram to bulkhead fitting

1. Because the hole is fragile, place the aquarium in the final spot before you install the bulkhead. Pass the bulkhead through this hole. The flanged gasket and gasket should be on the inside, while the locking nut will be on the outside. You can tighten the locking bolt with your fingers. Then, use pliers for final cinching.

Congratulations on drilling and opening your first aquarium. As a final note, make sure to use good quality hole saws and replace them often. The hole saws that we purchased can drill 8-10 tanks before the blades wear down. The more you use your holesaw, the more likely it is that the aquarium will burst while drilling. Get multiple hole saws to save your headache if you intend on drilling many tanks. Stock up on the bulkhead fittings you use in your fish store or home aquariums.