How to Fix Leaking Aquarium


Aquariums are an appealing addition to the interior of your house. The fish tank may please your eyes but demands attention and maintenance. The aquariums are made up of glass which makes them fragile. An aquarium owner must keep a keen eye on aquarium leakage to prevent further damage.

The leaking in the aquarium can start from a tiny pore and can lead to holes or cracks due to damaged aquarium sealant. If you leave it unattended then you may experience a minor flood in your room all of a sudden. The drops of water leaking can turn into a whole wave and gush out of the aquarium due to water pressure.

An aquarist must be ready and prepared for all sorts of situations. For instance, you should know how to fix leaking aquarium. Before that, you need to know the causes and ways to repair.

Why Do Aquariums Leak?

The worn-out or damaged silicone sealant makes the aquariums leak. The silicone sealant joins the glass walls of the aquarium. It holds the glass panes of the aquarium together to store in water. The silicone is strong enough to structure the aquarium but it can be worn out with passing time.

how to fix a leaking aquarium

If there are bubbles in the silicone sealant then its grip can be weak and cannot hold in water pressure for long. If the damage is severe then it can result in heavy leaking or water flowing out of the tank. However, you need not panic because this leaking problem can be controlled and you can repair the damage.

Moreover, if you get a low-quality aquarium, there are more chances of leaking water and sealant damage. So, it is better to get a good quality aquarium that has high-grade silicone used to hold the glass panes together. In this way, your aquarium can go a long way without cracks or leaks.

How To Spot a Leak in Your Aquarium

The easiest way to find the leaking spot is to mark the water level. If you find a decrease in the water level of the aquarium the next day, rest assured that you have a leaking aquarium. The key is to keep a close eye on the water levels as the water dripping will stop once it surpasses the leaking spot. So, you can confirm that the leaking point is above the current water level.

Use Paper Towel

A quick way of finding the leaking spot in your aquarium is to use paper towels. Wrap a paper towel around your aquarium and it will immediately get wet from the leaking spot. Once you detect the area of leak, mark it with duct tape, and fix it with instant sealant.

How to Fix the Leak in Your Aquarium

leak in fish tank

Now that, we know the source of the problem, let us move to its solution. If the problem is not massive, you can repair it at home. otherwise, you might have to take some professional help. However, you can follow the given steps to fix the leak in your aquarium.

Prepare The Tank

The very first step is to prepare your fish tank. For instance, empty or partially empty your aquarium to seal the leak.

The full draining of the tank water is required if the leaking spot is at the bottom level of the aquarium. For this purpose, you need to shift your fish into a temporary holding tank for the repairing time. Empty the tank completely and dry the surfaces.

However, if the leaking spot is at the upper level of the tank, then partial draining will work. You will not have to empty the whole tank. Remove the water with a help of a clean bowl or jar to avoid water contamination.

how to fix leaking fish tank

You can fix the leak without draining at all if the leaking source is quite small. For this purpose, you will need some baking soda and thin super glue. Plus, you can apply this fix from outside of the tank. It will buy you some time to find a more reliable fix or a new aquarium.

Scrape Away the Old or Broken Silicone Sealant

Silicone Sealant

You have to eradicate the root cause of leaking water which is the old sealant. Use single-edged razor blades for safety and to scrape the broken silicone. This razor blade scraper tool will do its job without scratching your glass walls or resulting in broken glass.

Moreover, if you have an acrylic tank, we would recommend you not use a razor blade instead, use a plastic blade scrapper. Remove all the old sealant to create room for the new sealant. Do not push hard on the sealant to avoid damaging the bond between the glass walls.

Clean the Scraped Area

Once you finish scrapping the old silicone, do not forget to clean the area. The new layer of sealant needs to have a strong bond. If you do not clean the area properly, there are fair chances that you may experience another leak in no time.

You can use acetone on a piece of soft cloth or paper towel. It will remove all the sealant residue and dirt with the damp cloth. It will help the new layer of silicone to sit firmly.

Preparations Before Applying Silicone 

To attain neatness and perfection in the application of silicone you need to map out your way. For this purpose, you need some painter’s tape to mark the leaking area.

how to fix an aquarium leak

Put the tape around all the tank seams. Take two cutouts of tape for each glass seam. Make sure you leave some space for sealant application between the tape and glass on each side.

Apply a New Sealant

The next step is to apply the fresh layer of sealant. For this purpose, you must get an aquarium-safe and non-toxic sealant to prevent your fish from any side effects. For precise and effective application of new silicone, you must apply it with a caulking gun.

Moreover, for the long-term benefits of sealant fixing, you should apply it from the inside of the tank to the leaking area instead of the outside of the tank. Afterward, smooth the layer with a caulking tool to ensure there are no bubbles of hangouts of silicone.

Smooth the Sealant

This step should be followed in the next five minutes of silicone application. You can use your fingers to spread out the sealant layer evenly. Or else, you can use a caulking tool. At this stage, you can remove the tapes.

Try not to use the excessive product as it would be difficult to manage and can leave loopholes. However, the lesser product is easily built up and gives more coverage. Hence, use thin layers of silicone and add more if needed.

Excessive product application on the seams can damage the seal and increase the repairing work.

Let the Sealant Dry

Once you have applied it, leave the sealant to dry completely. Ideally, it takes about 24 to 48 hours to dry and attain firmness with the glass walls.. The best trick to check the dryness is to sniff the smell of silicone. If there is no smell then it is fully dry.

Do not add water before the sealant is completely cured. Otherwise, its bonds will weaken and will be of no use and you will have to repeat the whole process all over again.

Refill the Fish Tank and Check for Leaks

The final step is to refill the aquarium and check for leaks. Fill the tank until the repaired or fixed leak area to check the effectiveness of the fixation.

how to fix a leaking fish tank

Ideally, you should wait for about 24 hours to be sure about the cure. Observe the aquarium and water level keenly during these hours. You can also use the same tricks that you used earlier to find the leaking spot.

Once you are sure that the sealant is cured, you can re-shift the tank’s inhabitants and plants from the temporary holding tank.

Final Thoughts

In conclusion, aquariums are a priced and attractive possession for aquarists. For this reason, one should maintain the aquarium religiously. The worst enemies of an aquarium are cracks and sealant damage. It can not only affect the water level but can also be a reason for tank breakage.

Either you have a glass tank or an acrylic tank both are quite fragile and prone to breakage. The leaks occur mainly because of old and broken sealants. These silicone layers loosen their grip and create space for the water to escape.

However, you can fix this problem with a new layer of silicone. Scrape off the old sealant, and clean and dry the area. Apply the new layer, let it dry, refill the tank and then check for leaks. Once you find no smell and leak, you can shift your fish pet back to its home.

Try to be a keen observer to detect the leaking spot timely and fix it before the damage worsens. Avoid using any toxic products the fixing the leak. Use aquarium-safe sealant or make some DIY fixes to earn some time for a new tank.

Be proactive in maintaining your aquarium well, so that you need not spend your worth on buying new tanks time and again. We hope you find the tips helpful and use them in fixing your leaking aquarium.

Cody Mitchell
Cody Mitchell is a pet lover and a passionate pet writer. He has worked as a professional writer for over 6 years, with a focus on creating compelling content for pet-related brands. His work has been featured in major publications. When he's not writing, Cody can be found playing with his two dogs (a labradoodle and a cocker spaniel) or cuddling his cat.

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