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.
Everyone has a slightly different way to drill glass tanks – such as the usage of a drill press, mineral oil, dish soap, drilling from both sides of the glass, and more. 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. That being said, drilling glass has 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. We have found that the more thick the glass is, the less likely it will crack. Aquariums less than 40 gallons tend to have thinner glass, which can cause them to crack between 10 and 25% of the time.
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. 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 device’s screen. Next, rotate the sunglasses like a steering-wheel. If the glass has not been tempered, it will appear that the screen is changing from white to solid dark as the sunglasses are rotated. If the glass has been tempered, the screen will show splotches and stripes when the sunglasses rotate. This effect can be seen online in video examples.
Instructions for Drilling Aquariums
1. Place the aquarium sideways so that the tank wall is facing 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. You will need to take the wood from the tank. Drill a hole through the wood where the dot was. 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 wood now serves as a guide so that the hole saw will not move while drilling. 2. Once you have created the guide, place the wood piece against the tank’s side edge and rim again. Tape the inside of the aquarium where you see the hole so that when the glass hole is drilled, it will not fall out and crack your tank. Tape also reduces chipping, so the hole is relatively clean.
1. You can fill the hole with water. You will have to refill the hole with water as some of the water may leak out. Water helps to wash away the dust and keep the hole saw from overheating.
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. Plus, try to keep the hole saw completely level and do not let the drill tilt or else the hole may get 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. If the glass starts making a squealing sound, pour more water on the hole saw and into the hole in the guide. Next, drill more. 2. If the frequency of the grinding sound changes, it is likely that the glass hole has already or is nearing breaking 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. Do not touch the glass hole’s interior.
Diagram for 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. Tighten the locking nut with your fingers and then finish cinching it down with pliers.
Congratulations on drilling your first tank! Last note: Make sure you use high quality hole saws that are regularly replaced. Our hole saws can drill approximately 8-10 tanks before they start to wear out. 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. You can also stock up on bulkhead fittings that our family uses in our aquariums and fish shop.