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 have drilled hundreds of aquariums for our fish store and personal fish rooms, so we’ve experimented with all of these methods. This article will explain the tried-and true technique that we finally settled on. Drilling glass comes with its risks. 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. According to our experience, thicker glass is more likely to crack. Aquariums with a volume less than 40gallons are made of thinner glass. They tend to break between 10-25% of all cases.
Materials for Drilling Aquariums
– Glass aquarium with tempered Bulkhead. (slip x slide) – A diamond-tipped, swivel-tipped saw that matches the bulkhead size. – Electric drill. – Clamp. – Pitcher or water bottle. – Flat piece about 1 inch thick. – Sharpie marker. 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. To test if the side walls are made of non-tempered glass, place a laptop or cell phone inside the tank so you can see its screen through the pane of glass that will be drilled. Make sure the device shows a white screen. While holding a pair polarized sunglasses in each hand, you can look at the device’s screen. Next, rotate the sunglasses like 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. When the sunglasses are rotated, you will see splotches or stripes on the screen if the glass is not tempered. You can view video examples online that illustrate this effect.
Instructions for Drilling Aquariums
1. Place the aquarium so that the tank wall will face upwards. Line up the piece of wood against the side edge and the rim of the tank. The hole saw should be placed where the bulkhead will be. The hole should be low enough so that (a) the overflow or drain is at the surface of the water and (b) the locking nut of the bulkhead won’t hit the rim while tightening it. Also, mark the wood so you know which side of the wood is touching the rim.
1. Take the wood off the tank and drill a hole in the wood where you marked the dot. A hole saw made for wood is best. You can use the diamond-tipped saw to do the job, but the wood might smoke. The wood now serves as a guide so that the hole saw will not move while drilling. 2. Once the guide has been created, align the piece of wood against both the tank’s rim and the side edge. Then 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 helps to reduce chipping and makes the hole look clean.
1. Water should be poured into the guide hole. The water might leak out, so it is important to continue refilling the guide to ensure that the glass remains sufficiently hydrated. 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. 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. You want to gradually file your way through the glass. The drilling step could take between 5-20 minutes depending upon 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. If the frequency of the grinding sound changes, it is likely that the glass hole has already or is nearing breaking through. Although there may be some edges that are slightly jagged, the bulkhead’s gasket will completely cover them. Do not touch the glass hole’s interior.
Diagram for bulkhead fitting
1. The hole is somewhat fragile, so place the aquarium in its final location before installing the bulkhead. Place the bulkhead into the hole. Make sure the gasket, flanged head, and locking nut are facing the outside of the tank. Use your fingers to tighten the locking nuts and then use pliers to finish cinching them down.
Congratulations on drilling your first tank! Last note: Make sure you use high quality hole saws that are regularly replaced. The hole saws we bought can drill about 8-10 tanks before they wear down too much. Your hole saw will wear down faster than the aquarium. Save yourself the hassle of drilling multiple tanks with a set of multiple holesaws. You can also stock up on bulkhead fittings that our family uses in our aquariums and fish shop.