In the past I’ve always bought my tanks drilled if that is what I wanted. One day I asked myself, “why”. So I figured I would learn how to drill a tank and try it out for myself. No sense in paying extra for something that I can do myself. I practiced on a pc of extra glass I had left over from making my sump, just to be safe before trying it on one of my tanks. Here’s how I did it.
First thing you have to do is get yourself a quality drill bit meant for glass. I tried both Carbide and diamond bits and found the diamond bit to be a lot better. The carbide bit seemed to be good for only a few holes. The diamond blade worked extremely well, but you will pay a lot more for it. Select the bulk head flange that you want to use first so you can purchase the correct sized drill bit. Keep in mind, none of these bits can cut through tempered glass, nor can tempered glass be cut in any way. If you try to cut or drill tempered glass, you will break the glass.
After you have marked the location you want to drill the hole, you need to start the hole in the glass. This can be tough as the bit can bounce around the glass if you are not careful. What I found that worked best is to start by holding the bit against the glass at a 45 degree angle. Once it starts cutting in to the glass, slowly turn it until the entire face of the bit is flat against the glass. The bit should be starting to cut through the glass now. DO NOT put ANY pressure on the drill. If you do, chances are you will break the glass. Only use the weight of the drill itself.
Also, please do not forget to wear safe eye-wear and gloves when drilling glass
Once you have the hole started, stop drilling. Take some plumbers putty and place all around the hole. Fill this area up with water. You will need the water to cool bit and to keep down dust from the glass. Continue drilling until the bit has made it through the glass. Remember, do not put any pressure on the drill, let the bit do all the work. Also, be very careful using power tool around water like this.
It can take some time to safely drill a hole in glass so don’t try to rush it. The thicker the glass, the longer it will be. In this example, it took me about 5 minutes to cut through a 20 gallon tank. Once you are done you have to be very careful on how you clean up as there will be very very small fragments of glass. I had placed a towel to collect the fragments that fell once the hole was cut through and used a wet paper towel to clean off the top. I would also suggest letting everything dry off for a few hours followed by a good vacuuming of the area to collect anything you may have missed.
Place your bulk head flange on the tank and your done.
I drilled my 20 gallon QT. The reason I wanted this tank drilled is that I use this tank a lot for curing live rock and soaking dry rock before adding it to my tank. Having a bulk head flange means I don have to siphon water out any more, just open the valve. The next time I want a drilled tank I will have the option to drill the tank myself.
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