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Fish tank sprung a leak?

How to reseal a fish tank like a DIY expert

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So you have a leak in your aquarium. But why replace it when you can repair or reseal it? Read our guide to find out how!

How to fix a leaking aquarium: Identifying the leak location

A leaky aquarium can spell big trouble for your underwater friends. If you suspect you have a leak in your fish tank, your first point of action should be to conduct a leak test. To do so, simply grab a paper towel and run it slowly along all the seams of your fish tank. If the water is leaking, it’ll transfer to the paper towel and you’ll be able to identify the exact location of the leak.

Close-up of hands using a scraper tool to remove old sealant from a glass aquarium corner.
Wondering how to reseal your fish tank? Use a scraper tool first to carefully clear the edges, ensuring a clean surface for the new sealant to adhere properly

How to seal a leaking fish tank: Step by step

If your aquarium’s seal has been compromised, you’ll need to reseal your fish tank. Here’s what you need to get the job done:

  • A waterproof (and fish-safe) silicone sealant
  • A sharp tool, such as a straight razor, for removing old sealant
  • Acetone
  • An old rag
  • Plastic containers to hold your fish and underwater plants while you’re working


Then, complete the following steps to reseal a fish tank:

  1. Remove your underwater friends and then completely drain the tank.
  2. Clean the tank with soapy water.
  3. Remove the old sealant in the leak location with a razor or other sharp tool and any remaining residue with acetone or nail polish remover.
  4. Apply approximately 6 mm of aquarium sealant along the outside of the joint that’s leaking as stated in the technical data sheet of the product. 
  5. Repeat the process to the inside of the joint and all other joints that are leaking.
  6. Allow for plenty of cure time before refilling your aquarium with water (check product instructions).
  7. Once cured, it’s time to refill your aquarium! Refill the tank approximately 7.5 cm at a time to maintain water pressure and ensure the seal is secure.


Pro tip! Make sure the entire joint is resealed on the inside and outside and that no air bubbles become trapped in the seal. This helps reinforce the strength of the sealant.

Hands applying sealant to a glass aquarium corner using a caulking gun.
How to reseal your fish tank? Start after clearing the edges by applying a smooth bead of silicone along the edges for a watertight seal.

How to reseal an aquarium: Choosing a quality sealant

There are a few factors to consider when choosing a quality sealant to repair an aquarium leak:

  • Do you require a sealant that’s freshwater or saltwater compatible?
  • Does the sealant have a non-toxic formula that’s safe for fish and underwater plants? 
  • Will the sealant hold up under constant water pressure?


To answer these questions and make sure you’re selecting the right sealant for the job, always check the product information.

Products used

  • LOCTITE All Purpose Extreme Gel

    LOCTITE All Purpose Extreme Gel: Fast, Brutal, Persistent. This powerful, all-purpose adhesive is here for all your bonding needs.

  • LOCTITE Super Glue

    LOCTITE Super Glue: The extremely strong superglue by the Henkel-brand LOCTITE is ideal for smaller repairs in the house or crafting jobs.

  • LOCTITE Super Glue All Plastics

    LOCTITE Super Glue All Plastics: Permanent bonding of plastic surfaces. 2-part system with Activator and Adhesive.

  • Packshot front AU Loctite Super Glue Control Liquid
    LOCTITE Super Glue Control Liquid

    LOCTITE Super Glue Control Liquid: A squeeze bottle for controlled and precise application.

  • LOCTITE Super Glue Creative Pen

    LOCTITE Super Glue Creative Pen: Say goodbye to glue spills, sticky fingers and messy DIY jobs with the LOCTITE Super Glue Creative Pen.

  • LOCTITE Super Glue Glass

    LOCTITE Super Glue Glass: Perfect for glass repairs! Bonds glass to glass, metal, stained, and tinted glass. Dries transparent for invisible, strong bonds.

  • LOCTITE Super Glue Power Gel

    LOCTITE Super Glue Power Gel: Precision bonds that are quick and anti-clog for reliable repairs.

  • LOCTITE Super Glue Precision

    LOCTITE Super Glue Precision: Ideal for precise applications. Instant strength, transparent drying, waterproof, heatproof, and shock-resistant.

  • LOCTITE Super Glue XXL

    LOCTITE Super Glue XXL: Provides instant strength, transparent drying, anti-clog cap for durable, invisible repairs.

  • LOCTITE Universal Instant Epoxy Liquid 5 Minute

    LOCTITE Universal Instant Epoxy Liquid 5 Minute Transparent, Instant Mix, Multi-Material. Bond smooth surfaces and fill gaps fast!

  • LOCTITE® 222

    Low-strength threadlocker for the locking and sealing of small fasteners under 6.35 mm in diameter. Prevents loosening from shock and vibration, removable with hand tools.

  • LOCTITE® 243

    This iconic threadlocker locks and seals metal nuts and bolts to prevent loosening due to shock and vibration. Medium strength: removable with hand tools.

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