How to Fix a Leaking Aquarium Without Draining it

How to Fix a Leaking Aquarium Without Draining It

One of the major downsides to owning a glass fish tank is the likelihood of a leak to occur. No one wants a leaking aquarium in their home! A leaky fish tank can be a huge problem, particularly if you own a huge aquarium.

And if this issue is not fixed soon enough, it could lead to your entire fish tank breaking or large amounts of water wetting your home.

Leaks are often caused by some sort of failure or flaw in the tank’s sealant, which either occurs during the aquarium’s construction or as a result of wear over time (the sealant becomes weak and starts to peel away from the tank’s glass).

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This could result in small leakages (pinhole size) or major blowouts such as the ones that soak your carpet and even leave water penetrating through your floor and down to the basement.

If you notice any leakages in your aquarium, you should take the necessary steps to fix the problem as soon as possible. Pinhole size leaks are often fixable from the outside without necessarily having to completely drain the entire tank.

Major leaks, however, might call for the serious reconstruction of your aquarium.

How to locate a leak in your aquarium

You might notice that your tank is leaking, but can’t really trace the location of the leak. If that’s the case, the tips below will help you in finding the exact location of the leak in your tank.

First, begin by checking your tank’s water level. If there’s a leak, your water level will drop past the leak and not any further. This way you will know that the tank’s leak is somewhere just right above where your water level stays constant. If you are still not capable of locating the leak’s position, you’ll have to conduct a bit of inspection on your tank.

Try to check for any disconnected parts or clear breaks in the sealant. Next, proceed to wrap a paper towel around your aquarium and closely observe where it gets wet; that’s the position of the leak.

Step by step guide to fixing a leaking aquarium

With the help of this guide, you should be able to fix your leaking fish tank without necessarily having to drain off all the water. Let us get right into it.


Step 1: Prepare your tank


You cannot fix your tank without preparing it! After finding the exact location of the leak in your aquarium, the first step to fixing the issue is to prepare your tank. Just drain enough water from your tank so that the leaking area is exposed. You can either use a cup or bucket to get this done.

However, if you find that the leak’s position is quite low, you might be forced to empty your tank and transfer your aqua-pets to a separate temporary holding tank. Your fish may have to stay in the temporary tank for a few hours or days before the sealant is completely dry, depending on the extent of the damage.


Step 2: Get rid of the old sealant


The old sealant is the culprit here and so to fix your leaking tank, you will have to get rid of this sealant. You could use a razor blade scraper to scrub off the old silicone sealant. This is actually the best item to use as it does not scratch your glass tank, and it takes out the old sealant with a lot of ease.

Remember, you should only get rid of the sealant at the inside corner. Avoid touching the sealant that actually connects the two tank’s glass panes or else you’ll more or less destroy the entire tank.

Also, note that old and new silicone or sealant do not really bond well together. If this concerns you, then you are better off just scraping off all the old sealant inside your tank. Ensure that not even a tiny piece of the old sealant drops into your aquarium as this will only contaminate the water and subsequently negatively affect your fish.


Step 3: Clean up the region to be sealed


You have to thoroughly clean up the region that you want to seal. Note that fresh silicone will not stick to a dirty area. This means that if you do not clean up the region well, you will most likely end up with another leaking tank sooner rather than later.

To clean, use a bit of acetone and a soggy cloth to remove the old silicone. Wipe off all the dirt and residue until that region is completely clean.


Step 4: Seal the leak


It’s now time to cover up the leaking part. The most crucial thing to ensure here is that the sealant you are using is 100 percent non-toxic silicone. In addition, it should not contain any fungicides.

If you make the mistake of purchasing silicone that is not intended for such kind of use (sealing a leaking aquarium), you will only end up contaminating your water and poisoning your fish.

With the help of a caulking gun, slowly and carefully run some silicone along the leaking area. Next, use a caulking tool or a damp finger to smoothen the silicone. You do not want your sealant sticking out very far. If this happens, apart from being unpleasant to look at, your aquarium fish may also be tempted to bite on it.

And just in case you are thinking of repairing the leak on your tank from the outside, please don’t do it! Such a repair is usually more effective and successful when conducted from the inside.


Step 5: Allow your sealant to dry 


After application, you need to give your sealant some time to dry and cure. If you make the mistake of adding water back into your aquarium before your sealant completely cured, the entire repair process would be for nothing; the sealant will become soft, peel, and result in a leak once again.

Silicone needs approximately 24 hours to dry up, but to be on the safe side, leave it for about 48 hours to completely cure. To accelerate the drying and curing process, you could use a heat lamp. However, be careful not to heat your silicone using temperatures that are higher than 110 degrees as this will melt or degrade your silicone.


Step 6: Check for any leaks


It is time to finally fill your aquarium back up. Fill it up a bit past the mark where you detected the leak. Note that both the weight and the pressure of the water are important factors here. That said, you need to wait for approximately one hour after filling your aquarium with water past its previous leaking point, the proceed to fill it up a bit more and wait for an extra hour.

If no leaks are detected, fill your tank all the way up and wait a little bit longer. And if you aren’t sure about whether or not your tank is still leaking, you can place a paper towel at the point where the leak used to be and observe if it remains dry or gets wet. 

If no leak is detected, you can proceed to set up your tank and return your fish back in.

On the other hand, if your tank is still leaking, you’ll, unfortunately, have to repeat this entire process all over again. Some people, however, just give up at this point and decide to purchase another tank.

What to do to prevent your aquarium from leaking

There are a couple of things you could do to ensure that your fish tank does not leak. Below are some useful tips:

  1. Make use of kid gloves when handling your fish tank
  2. Ensure that your aquarium is completely flat and level too
  3. Ensure that all rocks contained in your tank are tied down or fastened. In addition, do not just move your aquarium with rocks inside it
  4. Avoid moving around your tank when it has gravel or other kinds of hard décor inside
  5. Do not fill up your fish tank past the recommended water level. Note that water is weighty

All in all, most aquarium leaks are usually as a result of low quality or improper seals. In fact, in most instances when your fish tank leaks, you probably had absolutely nothing to do with this.

Final thoughts

As an aquarium hobbyist, you need to know which kind of leaks are fixable and which ones aren’t. The leaks that occur along your tank’s corners and are as a result of poor sealant are fixable. However, if your tank is cracked, for instance at the bottom or side pane, you’ll, unfortunately, be forced to get a new tank; such kinds of leaks cannot be fixed.

You will have to contact an expert to replace the entire pane, which in most cases ends up being more costly than just purchasing a new fish tank. Once your aquarium glass is cracked, the aquarium’s water pressure will only worsen the crack (make it bigger), which is normally what happens even after getting the original crack fixed.


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