DIY: How To Reseal Your Aquarium 5

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Do you have a leak in your aquarium? Looking for ways to do it for cheap?

Not to worry, today we’ll take a look at how easy resealing your aquarium really is (or can be). It may look like a daunting task at first but once you break it down, it’s quite simple really.

This DIY guide I’m posting below is one of the guides written by Nick Spinelli that I had turned into PDF quite awhile ago when I had trouble with a leak in my old tank. I found it to be valuable in helping my solve my problem and I’m sure most of you would find it valuable too!

In this guide, Nick breaks it down to you step-by-step on how to reseal an old aquarium tank with pictures on how he did it. So, let’s get to it shall we?

Resealing an Old Aquarium Tank

Do you have an ugly old tank or a leaker? Or just one that you don’t think will hold water? I want to help you out with fixing this problem.

I will go through the steps you must follow to reline a tank and show you how to do it. I picked a real rough one up for free because of the shape it was in, and it took about 3 hours to reline it.

The Tank

A 25 gallon tank resealed in several places with various materials including Mono caulking, and poorly done.


A poorly re-sealed aquarium – a good candidate for a demonstration.

The Equipment

Here are the things you will need.

  1. Razor knife or utility knife blades,
  2. windex,
  3. paper towel,
  4. plastic scotchbrite pad/sponge,
  5. and depending on the size of the project either a squeeze tube or a caulking gun and a tube of aquarium safe silicone
  6. and a vacuum for removing the debris.

The equipment you will require

The Steps

First you will want to clean the glass and remove any dirt etc. from the tank. After that you are ready to start removing the old silicone or what ever it is that was used. Place the edge of the blade against the glass at an angle and slide it under the silicone cutting toward the face that is butted against first. This will take several passes before you will reach the oposing glass.

Next cut into the silicone from the other face; be careful not to cut into the joint between the two panels. When you have cut deep enough the silicone should come out in large lengths or pieces. If you make diagonal cuts in the bottom corners it is easier to clean them out.


Above photos – removing old silicone and sealer

Above photos – removing old silicone and sealer

Your tank at this point should resemble the photos above. Vacuum out the debris, clean the glass with glass cleaner (not the foaming spray as it leaves a residue), and you are ready to start taping.

Starting with the bottom, place pull tabs in each corner. Then place your tape approximately one quarter inch back from the joints all the way around.

Note the pull tabs in the corners made of masking tape

Note the pull tabs in the corners made of masking tape

Next, tape the sides. Start with the verticle runs first so that when you pull the tape it will lift the bottom run as you go. After this is done trim out your corners.

The tank is now ready for re-sealing

The tank is now ready for re-sealing

The tank is now ready for re-sealing

Now you are ready for the new silicone. Cut the tip of the nozzle at approximately forty five degrees with a quarter inch opening. I apologize that is hard to see in this photo.

Lay a quarter inch bead all the way around

Lay a quarter inch bead all the way around

Lay a quarter inch bead all the way around.

New silicone has been applied

New silicone has been applied

Press it in and smooth it with your finger – working everything in until it is fairly even and smooth.

It is very important to remove the tape immediately after smoothing. Other wise you will have tape siliconed to your glass and have dificulty removing it.

And the finished result should look like this. Wait at least forty eight hours before filling.

The finished product - a newly resealed aquarium

The finished product – a newly resealed aquarium

One final note – if you accidently get silicone on the glass, leave it to cure for twenty four hours and it will peal off easily with a razor blade.

Your Thoughts?

The community would love to hear your tips and tricks if you guys have attempted this before. Or perhaps you have a few questions that you’d like to ask the Home Aquaria community. Feel free the post them in the comments section below.

Hope you have found the guide above helpful in your quest to reseal the stubborn leak on your aquarium. Know of anyone that might benefit from this guide? I’m sure they’d be happy if you shared it with them too. I know I would.


About Dennis Hanson

Dennis is an experienced aquarist with many years of knowledge and experience in keeping successful tanks. He also has no relations to the pop group Hanson.

5 thoughts on “DIY: How To Reseal Your Aquarium

  1. Pingback: How to Fix an Aquarium Leak Yourself - Blue Planet Aquarium

  2. Reply kailash rava Jan 6,2016 12:27 pm

    i didnt understand the cutting part.. how to peel the silicon with blade leaving the joints???

  3. Reply Louise M Feb 18,2016 7:09 am

    What silicone do you use?

  4. Reply B. Knight Jun 15,2016 3:56 am

    I have a reef ready tank; do I need to remove the overflow boxes before I re-silicone?

  5. Reply P.Hines Mar 1,2018 10:08 pm

    So , GE said that their silicone has mold & mildew inhibitors in their silicone and it will leach into the water & kill the fish….#1) How are your fish doing & #2) does the GE construction 1200 sealant series not have the mold & mildew inhibitors?

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