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How To Reseal An Aquarium In The Most Effective Way

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You come back home and find your aquarium leaking? If you are considering buying a used aquarium because a new one might be pricey, resist! This article will guide you on fixing the aquarium leakage that too cheap!

Leaking aquariums are an absolute mess, especially if your tank is a big one. Time to reseal it. Certainly, it may seem intimidating initially, but once you commence it, it’s duck soup.

How to reseal an aquarium and the efforts involved in doing so depends on the aquarium’s size. Resealing is done using an aquarium sealant and other essentials like a knife blade, sponge, paper towel, and vacuum.

What you’ll need to reseal an aquarium?

The stuff you use for resealing counts! Make sure to get the best quality products and tools to maximize the usage tenure of the sealed aquarium. If you tend to compromise on the quality, you are likely to have constant leakages.

Equipment required

  • A razor knife or some utility knife blades
  • A glass cleaner
  • A squeeze tube or a caulking gun
  • Aquarium sealant /aquarium-safe silicone
  • A masking tape
  • A paper towel
  • A sponge
  • A vacuum for removing the debris

Did You Know?

Humidity slows down the silicone/sealant curing process.

acquarium-sump-installed

Procedure to reseal an aquarium

I know, all this while...you are quite tensed about carrying out this so-called “tedious task.” But hey, your effort is totally worth it! This is gonna make your aquarium ever new. You have my word for it.

Here’s how to reseal an aquarium - a step-by-step guide!

1. Cleaning

Before you start resealing, make sure to clean the aquarium glass with a glass cleaner and sponge. Also, spread a paper towel below to avoid a mess.

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2. Removal of old sealant

After the glass is clean, start removing the old silicone or aquarium sealant from the aquarium with the help of a razor knife. Make sure to scrape out every corner. Once you are done with one side of the seal, repeat the same procedure on the other side. You may use pliers to grab any leftover dirt from the corners.

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Pro Tip


Do not repair your aquarium in humid conditions as the masking tape will not stick well. This may cause the glass to move before the sealant can set up.

3. Tape Up

Start taping up the area with masking tape or painter’s tape. You must start with the bottom and place the tape about a quarter inch back from the joints of the tank. Tape the sides by starting in vertical runs.

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4. ​Seal it out

At this point, your aquarium is ready for sealing. Apply the sealant or silicone on the sides of the tank. You must ideally start from the bottom bringing the silicone/sealant upwards.

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5. ​Use caulking gum if required

If you are wondering how to reseal a large aquarium, use a caulking gun to apply the sealant or silicone. The rest of the steps are similar.

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6. Flatten

Once this is done, use your finger to flatten the freshly applies sealant until it gets reasonably even.

7. Immediate tape removal

You must immediately remove the tape after this; otherwise, the silicone/ sealant will get taped to the aquarium glass. This will make it very difficult to remove the tape.

8. Let Dry

After you are done, let it dry for 24 to 48 hours before refilling it. DO NOT refill the tank with water before 24 hours as all your efforts will be in vain.

9. The final test

Lastly, test the tank after the silicone or sealant has completely dried up. Fill half of the tank first and keep an eye on it for considerable hours. This step is optional but is highly recommended to avoid recurring leakage.

Pro Tip


If you accidentally spill silicone or sealant on the glass, leave it untouched for 24 hours. It will peel off easily with a razor blade.

old-tank

Resealing an old tank

A few downsides of having an aquarium are its potential to leak as well as its glass breakage. For a new aquarium, leaking might not be a problem unless there’s a flaw in its sealant. But an old aquarium, whose silicone/sealant has become weak over time and has started peeling off, leakage is very likely to occur.

The size of the leak ironically varies from small pinhole size to major blowout, which could result in an empty tank, drenched carpets, and in the worst-case, water leaking down the floor to the basement.

Mostly, pinhole-sized leaks can be fixed from outside without draining or tearing the whole tank. On the other hand, bigger leakages may intimidate you. Relax! How to reseal a leaking fish tank is not as difficult as it looks.  However, you must avoid some common mistakes that people tend to make.

Precautions for resealing an old tank

1. Aquarium-safe sealant

Use a non-toxic sealant. Pure silicone sealant is the most preferable for an old tank.

Did You Know?

The purest form of silicone has the same crystal structure as that of a diamond.

2. Hyper clean

Old tanks tend to have stubborn seal residues even after cleaning. You must clean the glass surface adequately.

3. Pinpointing

An old fish tank leaking from the bottom may not always be the case. Pinpoint the exact location of small leakages.

4. Timeliness

The smallest of leakages should be fixed immediately. This is because in older tanks these pinhole leaks can form major blowouts if ignored.

5. Quantity

You must use an adequate amount of silicone sealant. A little more for an old tank particularly.

Does the size of a sump matter?

Yes, of course, the size of an aquarium sump matters in the procedure of how to set up an aquarium sump. This is because of the fact that the sump is used to hold the spilled water from the main tank. And especially in case of a power failure the drained water from the plumbing, filters, etc all comes down into the sump, Hence, it should be ready to hold all of it till the power comes back on.

acquarium-sump-2

Cost of resealing an aquarium

Well, the main reason why you decided to reseal the tank on your own was to cut the cost. Hence it is fair enough for you to enquire about the price involved. Good News! If you opt to reseal a leaking aquarium on your own, the expenses are the least. All you need to pay for is a sealant or silicone. A good quality sealant will cost you about  $13 to $15. The rest of the elements like glass cleaner, razor knife, sponge and vacuum are easily available in every household. Didn’t I tell you resealing is cost-effective? Save those bucks for that pretty black dress!

How long does a fish tank last?

If at all you are resealing your aquarium, it is most probable that your tank is an old one. While resealing an aquarium you may have other questions like “How often to reseal an old tank”? or  “How long does a fish tank last?”

Well, a tank’s lifespan is a debatable question as every individual case may vary. To be honest, a well-maintained fish tank can last for decades. Instances have shown people using the same aquarium for 40 years. Yes, 40 years! But again, this may not imply to all cases. Moreover, a glass fish tank lasts longer than an acrylic one.

Yet again, maintenance is not the only element in the tank’s life span. You maintain your aquarium excellently and follow a strict routine still your tank did not last long. This may be because of its manufacturing defects. There’s a vast difference between today’s aquariums and the ones that were made 40 years back. The materials used today may not be as great as those used ages before. Besides, the older the fish tank, the more care and maintenance it requires.

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Video Introduction

The Final Note

While altering the appearance of aquariums with beads and plants can be fun, repairing it can be tedious. The leakages, in particular, can bother you a lot. This detailed guide on how to reseal a fish tank is sure to ease your work. You can thank me later..haha! But on a serious note, resealing an aquarium can haunt you if not done properly.

A well-maintained aquarium has great visual aesthetics and enhances your home decor. On the other hand, a leaking tank is capable of putting your impression at stake! Be alert and act fast in such cases.

Top Editor's Choice on Reseal An Aquarium

SaleBestseller No. 1
GE GE012A Silicone 1 All Purpose Sealant Caulk, 10.1oz, Clear
GE 100% Silicone is 100% waterproof and 100% weatherproof.; Permanently flexible to keep gaps sealed, shrink-proof and crack-proof
Bestseller No. 2
How To Fix Leaking Fish Tank: Reseal A Leaking Aquarium
Amazon Kindle Edition; Clark, Harry (Author); English (Publication Language); 06/08/2018 (Publication Date)
Bestseller No. 3
Clear Aquarium Silicone Sealant - 10.2 Fluid oz Cartridge
Formulated for use with fresh and salt-water aquariums or a Vivarium
Bestseller No. 4
Aqueon Fish Tank Silicone Sealant, 10-ounce, Clear
100% silicone aquarium sealant is easy to apply and waterproof to stop leaks; High strength silicone creates a waterproof, permanent seal that will not crack or shrink
Bestseller No. 5
Aqueon Hang-On Overflow Box, 125-Gallon
Any aquarium up to 125 gallons; Ready your aquarium for advanced sump filtration; No need to empty the aquarium or drill holes
Bestseller No. 6
Fluval 10528A1 Evo V Marine Aquarium Kit, 5 gal
Five gallon glass aquarium for saltwater fish; Stylish honeycomb design conceals back filtration area while looking ultra modern
Bestseller No. 7
Penn-Plax Water World Radius Curved Corner Glass Aquarium Kit, 7.5-Gallon
Includes 10 led light; Cascade internal filter; 7.5 Gallon capacity
Bestseller No. 8
(Pack of 2) Aqueon Silicone Clear 10.3 Ounce each
Pack of Two 10.3oz Aqueon Silicone Clear; Our 100-percent silicone aquarium sealant is easy to apply and waterproof to stop leaks
Bestseller No. 9
Black Aquarium Silicone Sealant- 10 Oz Cartridge
Aquarium Silicone Sealant; Harmless to Fish When Fully Cured; 10.2 Fluid Oz Cartridge
Bestseller No. 10
Marineland 31003 Silicone Squeeze Tube, 2.8-Ounce, 85.05-Gram
Squeeze tube; Make sure area is dry before use; 3-Ounce; Squeeze tube; Make sure area is dry before use

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