How To Fix A Leaking Aquarium With And Without Draining

How To Fix A Leaking Aquarium With And Without Draining

Irrespective of how fun and exciting the hobby may seem, a leaking tank is one of the worst nightmares for any aquarist. This reveals the poor state of the aquarium sealant, decreases the quantity of tank water, and endangers the fish, shrimp, and other critters in the aquarium.

Obviously, these incidents require prompt attention like cleaning the aquarium, stripping off the old silicon, putting a new one, and reassembling the tank back after 24-48 hours. However, in some cases, we can do it faster and easier!

A glass tank is quite prone to wears, leaks, and cracks, and when this happens, it creates a path for aquarium water to escape from the tank. A leaking aquarium is a severe problem and it is most commonly caused by a wear or damage to the aquarium sealant. However, the good news is that aquarium leaks can be easily traced and fixed with the right directions.

In this article, we will be discussing how to fix a leaking aquarium with/without complete draining of the aquarium water. So, without further delay, let’s get right into it.

Why Do Aquariums Leak?

Aquariums tend to leak when the sealant present in the joint areas or seams are worn out, torn, or damaged.

By sealant, I mean the silicone that connects the glass panes of the aquarium. Essentially, its role is to hold the panes together to form the enclosure and also to prevent water from leaking out through the visible spaces at the seams.

Unfortunately, the sealant in the aquarium has the tendency to become weak, worn out, or broken after a long period of usage. This makes it possible for water to leak heavily or trickle out of the aquarium (depending on the leak’s magnitude), hence the need for a good fix to put the leaking situation completely under control.

How to Detect a Leak in Your Aquarium

There is a possibility that eventually your aquarium would be leaking, yet you may not be able to detect the leak by merely looking at the seals.

To detect the leak, you need to employ the following steps:

  • Monitor the water level closely. Usually, the water level will drop below the leaking spot and remain that way. So, this hints at the point of the leak being slightly above the present water level. You need to carefully check for breaks or damages in the sealant till you locate it.
  • Alternatively, you can add more water to the aquarium to increase the water level. Now, wrap a paper towel around the aquarium (sealant), and observe closely to notice the wet part, this sign gives away the leaking spot.
  • Once the leak has been identified, mark it with duct tape or marker pen, then move on to seal it with a good aquarium sealant.
Important: Turn off electricity, if there is any chance that water can come into contact with it! Your risk of receiving a shock is greater if you stand in a puddle of water.

Recommended Supplies

Depending on your situation, you may not need all these tools and materials.

  • Сaulk gun,
  • Blades,
  • Painters tape,
  • Aquarium Sealant,
  • Paper towels (or a soft cloth),
  • Superglue,
  • Baking soda,
  • Acetone.

How to Fix the Leak

Having looked out at how to detect a leak in the aquarium, let’s move on to how to fix the leak:

1. Prepare the Tank

Before fixing the leak, you have to get your tank ready. Also, there are three options available for this, either fixing without draining, with partial draining, or with draining (I’ll talk about at the end of the article).

Fixing the Aquarium with Draining

It’s best to drain the water completely if the leaking spot is located near the bottom of the tank.

This should be done using a siphon, after that, tear down the whole tank — remove the substrate, plants, décor, and equipment, and transfer your fish to a temporary holding tank pending the fix.

Now, you have an empty tank to repair, proceed with the rest of the steps.

If you have an emergency situation on your hands and do not know what to do with your livestock, you can read the article – “How To Setup an Easy Quarantine Tank”.

Fixing the Aquarium Without Full Draining

The ideal fix for relatively little leaks. Here, you are required to remove some of the tank water to ensure that the leaking spot is clearly above the water level.

You don’t have to drain the water completely if the leaking spot is at the upper level of the aquarium. Make use of a clean bowl to take few scoops of water out of the tank, and that should be enough to allow you to work on the leak.

Scrape an inch or two off the leaking area and apply a thin beam of fresh silicone sealant around the seam to reinforce it, then wait 48 – 72 hours before topping the aquarium with freshwater.

This method works best for a small leak on one seam. Several leaks will demand you to drain the tank water completely, then take away all aquarium interior to be able to remove the leaky seals or the whole sealant for proper replacement.

2. Scrape Away the Old or Broken Sealant

How To Fix A Leaking Aquarium With And Without Draining - razor bladeSince an old or broken sealant is often the cause of the leak, you have to scrape it away from the tank glass.

Use a razor blade scraper to gently scrape away the sealant from the edges. Razorblade scraper is the perfect tool for this purpose because it does a good job at peeling off the sealant without scratching or cracking the glass tank.

Warning: While at it, try as much as possible to avoid cutting yourself. Remember to use a plastic blade for acrylic tanks as a steel razor blade and abrasive sponges can easily scratch the surfaces.

Make sure to scrape off all the old sealant as it may not bond well with the new one, the aim is to remove the old sealant entirely to make way for the new one that would be applied subsequently.

Important: Do not push the razor blade too hard into the silicone! You do not want to break the seam in between the two glasses of the tank. Only silicone is responsible for the leaking, while seams just hold the tank glasses together.

3. Clean the Scraped Area

After removing the old sealant, follow-up by cleaning the scraped area thoroughly to provide optimal conditions for the new silicone sealant to adhere strongly to the surface.

If the area is not properly cleaned, the new sealant may not stick firmly to the tank glass thereby prompting the likelihood of encountering another leak in no distant time.

Important: You cannot use new silicone over old silicone! They do not stick well together.

Simply apply a little quantity of acetone to a soft cloth or paper towel, clean the area and allow it to dry.

Doing this helps to get rid of all residue and dirt on the scraped area, thereby making it clean and ready for a fresh sealant application.

4. Preparations Before Applying Silicone   

How To Fix A Leaking Aquarium With And Without Draining - painters tapeAfterward, in order to make the process of resealing easier, use painter’s tape or anything similar to map out the tank’s edges (seams). This provides guidelines to help attain a straight-line finish when spreading the silicone.

Cut two strips of tape for every seam. Leave some space (5-10 mm or about 3/8”) between the glass and the tape on each side.

5. Apply a New Sealant

How To Fix A Leaking Aquarium With And Without Draining - Apply a New SealantThe next step is applying a fresh aquarium silicone sealant to the leaking area, before this application you should ensure that you have a non-toxic, 100% silicone sealant as it prevents harm to your fish since some brands contain fungicides.

Important: Use aquarium-safe silicone to fix the leaks, and make sure that you apply it from the inside of the aquarium as it is more effective and long-lasting than outside application.

The right way to do this is to apply the silicone sealant on the leaking area using a caulk gun (link to check the price on Amazon).

6. Smooth the Sealant

Afterward, use a caulk tool, flat plastic, or your fingers to smoothen the applied sealant evenly from one end to the other. Next, remove the tape.

Desist from applying too much silicone on the seams as any extra/protruding piece may ruin the seal, and your fish may chew the piece out of curiosity. So, it’s advisable to spread a thin layer gradually and increase it if need be.

How To Fix A Leaking Aquarium With And Without Draining - aquarium sealantYou need to do this step in the next 5 minutes before the silicone cure.

Examples of aquarium sealant (check the price on Amazon)

If you have a small leak and do not need that much silicone, in this case, one of these tiny tubes will be a better choice. However, it is strongly recommended to buy twice as much as you need.

–         Tub Clear Silicone Waterproof Sealant

–         Aqueon Silicone Sealant

7. Let the Sealant Dry

At this point, you have to give the silicone adequate time to dry well before filling the tank up with water.

Follow the instruction on the product label.

Though 24 hours is quite enough for the silicone sealant to dry and cure, you may as well extend the wait for 48 hours to be sure that it is completely cured. You will also notice that it does not smell anymore.

Important: Reseal your tank only in a well-ventilated area! It is definitely not pleasant. Silicon smells like vinegar because silicon has acetic acid, this substance is vinegar.

Adding water to an uncured sealant will weaken it and that’s definitely the last thing anyone wants at this point.

8. Refill the Aquarium and Check for Leaks

The ultimate step is to refill the aquarium with enough clean water to push the water level past the fixed leaking area.

If possible, allow the water to sit in the aquarium for about 24 hours for best observation, during this period you can truly ascertain whether the aquarium still has any leaks.

The absence of leaks suggests that it’s time to reassemble the aquarium and reintroduce the inhabitants.

Fixing the Aquarium Without Draining at All

In most cases, this is the most problematic issue because not all of us have time or opportunity to move the animals or corals to a temporary holding tank.

Unfortunately, we can try to fix the aquarium without draining only if the leaking spot is a small trickle (1 inch or 2.5 cm at most).

The main advantages of this method:

  1. This method can help you if the leaking spot is at the lower level of the aquarium.
  2. It is almost instant. We do not have to wait 24-48 hours.
  3. In addition, we can do this outside of the tank.

You will need (links to Amazon):

–      Super thin super glue (like Ultra Gel Control Super Glue or Insta-Cure 2oz Super Thin

–      Baking Soda

How To Fix A Leaking Aquarium With And Without Draining baking soda methodYou can use any other super glue just make sure it is about water consistency, that it is a thin superglue.

  1. Sprinkle baking soda on the leaking spot.
  2. Use super glue on the spot. I repeat – the glue must be super thin and run like water.
  3. Baking soda will absorb the glue and almost instantly make it dry.
  4. Repeat the process a few times to make 3 – 5 layers.

The composite bond of the superglue and the baking soda is extremely strong and it will stop the leakage in no time.

Note: Whenever it is possible, I would still recommend draining the water to the point where the leaking spot is clearly above the water level. However, unlike the previous method, we can reseal the tank and fill it again within minutes!

The downside of this method is that super glue does not expand and contract like glass. Therefore, if the temperature changes, there is a risk of cracking the glass.

So, despite its effectiveness, I would not consider this a one-time fix at all. It will just buy you some time to get another tank started or do something else to fix the problem. 

How do you fix broken glass in an aquarium?

If the aquarium is cracked, then the problem is even more serious.

The fact is that cracks tend to grow under hydraulic pressure. A small chip somewhere in the corner of the aquarium can very quickly spread to the entire length of the glass.

Therefore, you will have to replace the cracked glass with a new one.

Unlike seal leaking, generally, it is not even recommended to fix it. However, if you just need some time, you can still use the methods described in this article. The only problem is that their efficiency will be lower.

How to Prevent Leaking

There are several things that you need to know about your aquarium.

–         Flat surface

Level your aquarium. Ensure that your aquarium is sitting on a flat surface. All 4 corners of the aquarium must have stable contact with the surface.

Otherwise, when the aquarium is not leveled and/or one of the corners is not touching the surface, it will cause twisting in the frame of the aquarium. As a result, it will create additional pressure on the seams and then leaking.

I would like to remind you that a gallon of water weighs 8 pounds. So a complete hundred-gallon system can easily weigh over a thousand pounds! The pressure is huge!

–         Age of the tank

Silicone also exhibits aging in aquarium applications. The aging behavior is unpredictable and the older your aquarium the higher is the chance that you will have leaking problems.

Generally, problems start after 7-10 years. Therefore, check when the aquarium was built, so, you can reseal it.

–         Silicone test

If you have no idea how old your tank is you can test the silicone.

Touch the silicone with your nails. If you can slide the nails under it, like it is peeling off (you do not have to push them under the silicone, just slightly) – this is a sure sign that silicone is not good enough anymore.

Change the silicone before it is too late.

A few don’ts:

  • Do not use sharp tools during maintenance too closely to the seals. You can accidentally damage them.
  • Do not move your aquarium when there is water in it. It will create additional pressure on the seams.

In Conclusion

A leaking tank calls for urgent intervention, if not, you risk having a mini flood in your room and/or losing your aquarium fish. The seals of a fish tank get worn out or broken over time, so it’s crucial to detach the old sealant and apply a fresh one to keep the tank leak-proof.

This unusual problem affects old or used tanks more, but with our guide, you can reinforce your tank seams within the shortest time possible.

Execute the steps stated earlier and your aquarium leaks would be gone. However, if you discover cracks in the glass after a due inspection or the leaking problem persists in your aquarium after resealing the seams, do well to purchase a new aquarium.

Related article:

How to Clean an Aquarium Filter
How to Clean and Disinfect Used Aquariums and Accessories

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