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How to Fix A Leaking Aquarium Without Draining

Nothing is more annoying for a fish owner than a leaking aquarium. And for those who have carpets and rugs around the fish tank, it’s an absolute nightmare!

However, it’s a catch that comes with owning fish, and, at a certain point, it’s inevitable. That’s why all fish-owners should learn how to deal with the situation instead of being intimidated by it.

Essentially, there are two ways to fix a leaking aquariumThe first and the easy way is to fix the tank from the outside without draining it, and the other way it is fixed from the inside.

So today, you’ll learn how to fix a leaking aquarium without draining it!

Why Aquariums Leak

Before we get into fixing the aquarium, let’s take a step back and learn the basics first. If your aquarium is leaking, it’s essential to know why it has happened so you can prevent it from happening again.

And if you’re a new aquarium owner, understanding why it may leak is just as important to avoid the situation.

Hence, here are a few of the most typical reasons why an aquarium might be leaking:

Sealant wearing out

Possibly the most prevalent reason why an aquarium leak is because of the sealant.

The sealant refers to the silicone that is responsible for holding and connecting the tank’s glass panes. Its primary job is to hold the panes so close together that the water doesn’t leak out.

Needless to say, when the sealant starts to wear out, break down, or becomes weak over time, it stops doing its job, creating holes and leakages in the aquarium.

Depending on how damaged the sealant is and how large the hole is, water might trickle down or leak heavily.

Construction problems

Another common reason why aquariums and fish tanks start to leak is manufacturing faults.

If a fish tank is new and you have just started using it, it is highly likely that there are construction problems with the tank itself.

Pressure irregularities

If a fish tank’s weight is not evenly distributed, the base becomes weak.

As a result, the pressure becomes uneven, and as the fish tank grows old, there is a high possibility of an eventual stress fracture, which causes leaking.

In such cases, the leak usually happens from the bottom.

Impact and trauma

During transportation, storage, or while you are using it, if there is an incident of trauma, impact, or projectile, it might result in a leak.

It doesn’t necessarily need the glass to break; if the impact is on the panes and it is strong enough, it might cause leaks from any part of the aquarium.

How To Know That Your Aquarium Is Leaking


Now that we have talked about how exactly an aquarium might end up leaking, let’s start talking about how to fix a leaking aquarium without draining it.

The first and foremost step of this procedure is to know that your aquarium is, in fact, leaking. It might seem like it’s common sense, but many people don’t realize that their fish tank is leaking for hours and days at a time.

The leak is so small, and water trickles down so slowly that it’s hard even to notice.

Identify the leak and locate its exact origin. As simple as it seems, it’s actually quite a tricky task to do. Because more often than not, especially if the water is trickling down a path, it can be quite hard to tell where the water is actually coming from.

It’s even more complicated if there are multiple leaks in the aquarium. Hence, here’s how to know your tank is leaking and how to locate that leak:

  • Mark the water level on the tank’s glass so you can monitor it. If the level is continuously and considerably decreasing, it means there’s a leak somewhere.
  • If the water level drops and then stops decreasing at a certain point, it has now crossed the leakage point. Hence, look for this point somewhere above the current water level.
  • Another way to locate this leak is by adding more water to the tank and wrapping a towel around it. The part that starts to get wet immediately is where the water is leaking from.
  • Once you identify the point of leakage, get a marker or duct tape to mark it. This way, you won’t forget where the leakage was when you go and get supplies to fix it or wait for a professional to come and take a look.

How to Fix A Leaking Aquarium Without Draining – A Stepwise Guide

Evacuating the fish and removing the contents of the tank before fixing it can be problematic. Understandably, most people want to fix the aquarium without the hassle.

If the hole, or the leaking point, is around 1 inch to 2.5 cm, you can quickly fix it without having to drain the tank. Here’s how to do it:

  • Let’s say you have identified the leakage point. If it is somewhere around the top of the aquarium, remove some of the water from the top.
  • Ensure that the water level is below the point of leakage.
  • You may use a cup or a bucket for this purpose; whatever works for you!
  • Once there is no water above or near the leak, it will stop leaking, and you’ll have clear, complete access to the damaged area.

Next, there are two ways on how to fix a leaking aquarium without draining it:

Fixing The Aquarium from Outside

Things You’ll Need for this method:

  • Superglue (preferably super thin, like water)
  • Baking soda


  • You can use any super glue that you can get your hands on. Just make sure that it has a very thin, water-like consistency. The thinner, the better.
  • Sprinkle some baking soda over the leaking point.
  • Now, pour some of that super glue over the top.
  • You will notice that the baking soda absorbs the superglue almost instantly, and it will dry within seconds.
  • Now, add some more baking soda to it and pour some more superglue over the top.
  • Repeat this process for 3 to 5 layers until you notice a strong, thick composite forming.
  • The baking soda and super glue will bind together to make a powerful compound that will not only fill the leaking hole but will also bind the two ends of the crack.

The Pros and Cons Of This Method:


  • This method doesn’t require a lot of time and energy.
  • There is no need to wait for days or call a professional to take care of it.
  • It’s easy and straightforward, and you can do it yourself.
  • The leakage can be fixed from the outside, meaning that you don’t have to remove any of the tank’s contents or disturb the fish.


  • Unlike glass, superglue does not have the capacity to contract and expand under temperature change. Thus, the glass will contract and expand, but the superglue will not. Hence, there is a slight risk of the glass being damaged.

Fixing the Aquarium from Inside

Things You’ll Need For this method:

  • Razorblade
  • Acetone
  • Damp cloth
  • Sealant
  • Caulking gun


  • If the leakage is because of the old sealant wearing off or breaking down, scrape it off first. You can use a razor blade to do this. The advantage of using a razor blade is that it won’t be so sharp as to scratch the glass but will effectively remove the old sealant from the tank.
  • Now, clean the point of leakage so that the new silicone can stick to it nicely. Using a damp cloth and acetone and rubbing it over the point will do the job. It should be free of any residual sealant or dirt.
  • Get the new sealant (make sure it’s 100% non-toxic silicone).
  • Take your caulking gun and use it to apply the sealant to the particular area. Apply a generous amount of the sealant and make sure that the entire leaking point is covered.
  • Smoothen it out using a caulking tool so that the fish don’t nibble on it.
  • Allow the new sealant to dry. This part is more important than you think because if this new silicon doesn’t dry properly, there will be no point in making all the effort; the leak won’t fix properly!

The Pros and Cons Of This Method:


  • It’s more long-lasting than applying superglue with baking soda.
  • There is a considerably smaller chance of damaging the glass in the long run.


  • You can only fix the tank from the inside using this method.

Also Read: Betta Imbellis – The Peaceful Betta or Cresent Care Guide

Some Do’s And Don’ts Of Fixing The Aquarium

  • Do use a heating lamp advocate nearby to speed up the process of drying the sealant.
  • Once the seal has dried, do add more water to the tank to make sure that it is not leaking anymore. If it is still leaking, remove the water again and see what has been missed.
  • Do not add the new sealant to the old sealant because the two will not stick together. Instead of fixing the problem, doing this will result in further complications.
  • Do not put the water back into the aquarium until the new sealant has dried completely. If you do this, the seal will be ruined, and all the silicone will melt down, become soft, and peel off.
  • Do not work with the aquarium while it is connected to electricity. Turn the connection off and then work with it. If you’re standing in a puddle while the electricity is on, there’s a high chance of you getting a shock.
  • Do not use a toxic sealant or one that has fungicide in it; it will mix with the water and poison the fish.

How To Make Sure Your Aquarium Doesn’t Leak Again

Now that you know how to fix a leaking fish tank without draining it, you should learn how to maintain it so that it doesn’t happen again.

Use gloves

When you’re handling or fixing the fish tank, make sure you’re wearing gloves. It just makes the process safer for both you and the aquarium.

In addition, it ensures that you don’t hurt yourself if there is any glass breakage and prevents you from being harsh with the tank.

Level the aquarium

As mentioned earlier, if the aquarium is not entirely leveled or flat, and uneven pressure around the base can cause leakage.

To make sure that your aquarium doesn’t leak, keep the aquarium leveled so that the pressure remains even.

Fasten and tie down any rocks inside the tank

If you have any rocks, props, or other items inside the tank, they can hit the panels and the glass if they move around.

Children tend to be harsh when playing with aquariums and move them a lot. So, make sure that you fasten these props and tie them down if there is an earthquake or an impact.

Also, when you are moving the aquarium while cleaning it, fixing the rocks will make sure that they don’t move around while you’re at it.

Don’t overfill the tank

Excessive water can increase the pressure inside the aquarium; after all, water has its weight! Increased pressure or weight inside the tank can cause leakage, so don’t fill the aquarium over the recommended mark.

Inquire and check the tank before bringing it home

If you’re buying a used tank from someone, or even a new one, ensure that you take a good look at it before paying for it.

And, if you see any manufacturing faults or something odd about the tank’s construction, do not spend the money on it.

If you don’t want to deal with frequent fixings, make sure you purchase a premium aquarium in the first place.

Final Words

Whichever way you decide to fix the tank from draining, you must do it as soon as possible. The more time you waste before addressing the problem, the more damage might happen.

Besides, no one likes a large puddle growing under their beautiful aquariums!

On the other hand, if you feel like fixing the tank yourself is a risk, or you’re nervous about it, call a professional and let them do it for you.

This way you can avoid any trouble but obviously at the cost of a few bucks.

Fishkeeping Expert
Fishkeeping Expert
With years of collective fishkeeping knowledge, we are pleased to share the tank maintenance tips and fish care advice we've picked up along the way. Fishkeeping Expert is home to all fishkeeping tutorials and guides that will help you keep your fish healthy.


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