Fish tank sprung a leak?

How to reseal a fish tank like a DIY expert

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.

If the leak in your fish tank is coming from a crack in the glass, you’ll have to replace the entire pane of glass. While aquarium sealants can work miracles in resealing joints, they aren’t designed to hold broken glass together under intense water pressure.

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.

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.