How To Reseal an Aquarium

Have you come home to discover your aquarium has started leaking? If you have, don’t panic! This is actually a fairly common problem that usually results in a little water trickling from the seams of your tank. However, if left untreated it can lead to bigger problems.

If you’re a family with a few fishy members, then it’s likely you’ll experience issues with cracks or leaks in your aquarium at least once.

What’s even more likely is that you won’t want to spend money on replacing an entire tank or professional repairs, especially when resealing an aquarium can be done yourself! 

But where do you begin? This article aims to provide a step-by-step explanation of how to reseal an aquarium and some other information that any fish enthusiast needs to know.

Is It Worth It?

Before you start, it’s worth checking to see if your aquarium is in good enough condition to warrant being repaired rather than replaced. 

You’ll need to inspect the glass for cracks or chips that may compromise the integrity of the panel, as these cannot be fixed by simply resealing the aquarium. 

What You’ll Need

To start with, you’ll need a suitable workspace - somewhere that has some form of ventilation to help with the fumes and enough space to work comfortably. You’ll also require the following tools and supplies: 


  • Razor scraper, although a razor blade can be used if necessary 
  • A vacuum for removing debris 
  • Caulking gun
  • A clean cloth or dishrag 
  • Rubber gloves (optional)


  • Rubbing alcohol
  • Aquarium sealant 

When choosing an aquarium sealant, choose one that is nontoxic or 100% silicone and avoid any that may have harmful substances or chemicals. These could leak into the water once the tank has been filled which can cause serious problems for the inhabitants.

How Do I Reseal an Aquarium? 

Step 1 - Preparation

Once you’ve identified the areas which need resealing, you’ll be able to judge how much water needs to be drained. 

If the leak is near the top of your tank, you only need to remove enough water so that the crack is above the surface level in order to clean and dry the surrounding area. 

However, if it’s close to the bottom of your aquarium you’ll need to drain the entire tank and remove all of the rocks and debris using a vacuum. Don’t forget to find a suitable temporary home for your fish, first! 

Step 2 - Remove Old Silicone

Next, you’ll need to remove the old sealant using a razor blade scraper. Make sure you get all of the loose pieces and remove any silicone that was used for a previous repair, as sometimes new silicone doesn’t bond well to the old sealant.

It should come away fairly easily with the help of your scraper, but don’t worry if there’s some residue left behind as this will be taken care of in the next step. 

Step 3 - Cleaning

After you’ve removed the old silicone you’ll need to clean the area, as this will help to ensure that your resealing repair is successful.

Using a clean cloth and a small amount of rubbing alcohol, wipe around the area to sanitize the glass, and to remove any dirt or lingering silicone residue. 

Pat down with a paper towel and allow to air dry for approximately 15 minutes or until the area is completely dry. Next comes the slightly trickier part.

Step 4 - Resealing

Now it’s time to carefully apply your sealant to the required area. Run a bead of silicone along the leak’s seam on the inside of your tank, as this is more effective than sealing it from the outside due to the added pressure the water provides. 

You should use a caulking gun for this to achieve precise results, although if you have a particularly steady hand you may be okay without one. 

Next, you can use a caulking tool or simply a wet finger to smooth the silicone until it fully covers the crack that’s causing the leak. 

Step 5 - Allow to Dry

The final step in resealing an aquarium is allowing the silicone to completely dry and it needs to cure for at least 24 hours. 

Depending on the environment you’re working in and the size of the tank you’re resealing, it could need even longer before it’s ready. 

To speed things up, you can use a heat lamp to cure the sealant faster as long as you make sure the source of heat is below 110 degrees (F). However, it’s not a process you want to rush as this is vital in helping the silicone seal to the glass completely. 

If you refill the tank with water before the silicone is dry, you’ll have to repeat the whole process all over again!

What Will it Cost?

Done right, releasing an aquarium shouldn’t be an expensive task. That’s why many people opt to fix any cracks or leaks themselves rather than purchasing an entirely new tank or hiring a professional to do it for you. 

It’s difficult to give an exact cost estimation as this will largely depend on the tools and the type of sealant you use, plus the extent of the damage you’re attempting to fix. 

Typically you’ll be looking at about $20 in total for tools and materials, which will leave you prepared for any future resealing as well as you should have plenty of sealant leftover. 

How Many Times Will I Have to Reseal my Aquarium? 

This depends on how good a job you do the first time around, and if the silicone bonds well to completely seal the leak. 

Silicone has a long lifespan of 20-30 years, so if you’ve resealed it correctly you shouldn’t have to worry about repeating this process any time soon. 


While it may seem like an intimidating job if you haven’t had to do it before, we hope that this article has answered any questions you might have about how to reseal an aquarium. 

It’s a job you’ll want to get around to sooner rather than later, as maintaining your aquarium properly will keep it looking great as well as providing a happy home for your fish.