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.
Everybody has their own way of drilling glass tanks. This includes using a drill press or mineral oil. Some also use dish soap. Others may use a drill press. We’ve tried many different methods to drill aquariums for both our personal fish room and fish store. This article explains which technique was the most successful. However, drilling glass can be dangerous. We recommend wearing proper safety equipment, and we are not liable for any injuries, losses, or damages you may experience while undergoing this DIY project. In our experience, the thicker the glass, the less likely the tank will crack. Aquariums smaller than 40 gallons have thinner glass and tend to break 10-25% of the time.
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. You can check the side walls of your aquarium by placing a computer or mobile phone in the tank. The pane of glass will be drilled so that you can view the screen. You should ensure that the screen of your device is white. Look at the device screen while holding a pair of polarized sunglasses in your hands and then rotate the sunglasses as if turning a steering wheel. The screen will appear as if it isn’t tempered. It will shift from white to black when you rotate the sunglasses. If the glass has been tempered, the screen will show splotches and stripes when the sunglasses rotate. You can view video examples online that illustrate this effect.
Instructions for drilling Aquariums
1. Place the aquarium sideways so that the tank wall is facing upwards. Place the piece of wooden against the tank’s side edge. Position the hole saw where you want the bulkhead to be and draw a dot in the center of the hole. The hole should be positioned low enough that the overflow, drain, and locking nut of bulkhead don’t touch the rim when tightening them. You can also mark the wood so that you know which side touches the rim.
1. Drill a hole in the wood at the spot you have marked with a dot. (Ideally, you should use another hole saw that is meant for wood. The diamond-tipped holesaw will work, but it may cause some smoke. The guide is now used to make sure the hole saw doesn’t move when drilling. 2. Once you have created the guide, place the wood piece against the tank’s side edge and rim again. Tape the aquarium inside where you see the hole. This will ensure that it doesn’t fall out and cause damage to your tank when drilling the glass hole. The tape helps to reduce chipping and makes the hole look clean.
1. You can fill the hole with water. Some of the water will leak out so you will need to keep refilling it to keep the glass sufficiently wet. Water is useful to clean away dust and keep the holesaw from getting too hot.
1. Press the trigger of the electric drill until it spins slowly. Then, gradually increase the speed to moderate. Apply a light, even pressure on the hole saw, and let the weight of the drill to carry it downward. 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. Pour more water into the guide and onto the hole saw if the glass is making a loud squealing noise. Then continue drilling. 2. The frequency of the grinding sound changes indicates that the glass hole is close to or has already been broken through. Although there may be some edges that are slightly jagged, the bulkhead’s gasket will completely cover them. Take care to remove the tape and not touch the glass.
Diagram bulkhead fitting
1. Because the hole is fragile, place the aquarium in the final spot before you install the bulkhead. Place the bulkhead into the hole. Make sure the gasket, flanged head, and locking nut are facing the outside of the tank. Continue tightening the locking nut using your fingers, and then cinch it down with pliers.
Congratulations on drilling your first aquarium! A final tip: make sure to use high-quality hole saws, and that they are replaced regularly. The hole saws that we purchased can drill 8-10 tanks before the blades wear down. Your aquarium is more likely to break if you keep it in use for too long. If you plan on drilling many tanks, get a pack of multiple hole saws and save yourself the headache. Stock up on the bulkhead fittings we use in our home aquariums and fish store.