How to fix a leaky fish tank with aquarium silicone (2024)

A leaky aquarium doesn’t mean the end of your aquatic wonderland. Resealing your tank is simple with the right aquarium silicone. Our guide takes you through the steps of repairing a fish tank and directs you to the best aquarium safe silicone sealant.

What is aquarium safe silicone?

A leaky aquarium is a problem not to be ignored: if left unattended, a small leak can grow until the entire seam comes undone, causing damage to both your home and your fish.

When resealing your aquarium, it’s important to choose a sealant that will protect the habitat of your tank. Aquarium safe silicones have special formulas that differ from other silicone sealants. Here’s what to look for.

Aquarium safe silicone sealants

  • are saltwater and freshwater compatible
  • have formulas that hold up under continuous water submersion
  • are non toxic and 100% safe for an aquatic habitat.

How to apply aquarium safe silicone sealant

Before starting the repair, we recommend you check all the seams for secureness. If you drain the tank for one leak, it’s smart to check the integrity of the other seals while you’re at it.

  1. Remove water to a point well below the line you’re fixing. We recommend you remove the fish and completely drain and clean the tank.
  2. Remove the old sealant with a straight razor or another sharp tool. If your fish are still in the tank, avoid dropping silicone residue in the water. Don’t pull the silicone bead away unless you’re replacing the entire seam.
  3. Clean the joints to remove old stubborn residue from the glass. Consider using mineral spirits to completely remove any residue.
  4. Starting on the inside of the tank, apply your aquarium silicone bead into the seam along the joint. Take care to fill any gaps with the sealant.
  5. Repeat application on the outside of the tank, making sure you don’t have gaps in the sealant.
  6. Wait for cure time to be achieved before refilling the tank with water.
  7. Fill the tank slowly, while making sure your seam is secure.

Which aquarium silicone is best for the job?

For the best aquarium safe silicone, turn to Loctite Clear Silicone Waterproof Sealant. This formula can be used in saltwater as well as freshwater aquariums. It’s both flexible and gap filling, making it the perfect aquarium safe sealant for any tank with a capacity of up to 30 gallons.

If the glass itself is substantially cracked, seek the opinion of a professional. You might need a new pane of glass. Depending on the size of your aquarium, the sealant might not hold up to the water pressure in the tank.

How to fix a leaky fish tank with aquarium silicone (2024)

FAQs

How to fix a leaky fish tank with aquarium silicone? ›

Don't pull the silicone bead away unless you're replacing the entire seam. Clean the joints to remove old stubborn residue from the glass. Consider using mineral spirits to completely remove any residue. Starting on the inside of the tank, apply your aquarium silicone bead into the seam along the joint.

How to reseal a leaking fish tank? ›

How to reseal a fish tank: Step by step
  1. Remove the fish and completely drain and clean the tank.
  2. Remove the old sealant with a straight razor.
  3. Clean the old residue off with acetone. ...
  4. Apply a ¼” bead of aquarium sealant along the outside of the joint. ...
  5. Repeat the process on all other joints.

Is aquarium 100% silicone sealant safe for fish? ›

Will Not Harm Fish. Because our %100 silicone sealant is free from additives and ingredients that are known to cause damage to marine life, you can trust that our 100% silicone sealant will do no harm to your fish and other aquarium friends.

Is it worth resealing a fish tank? ›

If you have a very large aquarium that was custom built it might make sense to have it resealed. However, newer tanks may offer better features that still make resealing a poor choice. A quality silicone seal should last at least 10 years. A lot of upgrades in overflow boxes and drains can happen in 10 years.

How long does it take for aquarium silicone sealant to cure? ›

The cure mechanism begins as soon as the sealant comes in contact with the air. At conditions of 25°C (77°F) and 50% relative humidity, the sealant will skin in 10 minutes and fully cure in 24 hours (1/8” bead) and reaches its maximum adhesion in 7 days. Higher humidity accelerates curing.

What is the best way to seal a leaking tank? ›

Epoxy/ Putty to stop plastic tank leakage

It is one of the most popular, and highly effective methods to prevent water tank leakage. Pro tip - Asian Paints SmartCare FabSeal is a fast-curing epoxy compound that can be used for fixing water tank leaks, plugging holes, and repairing cracks.

How to stop water leakage from a fish tank? ›

How to reseal an aquarium. Using aquarium silicone, apply an even bead across the place where the leak is. If you want to be doubly sure, apply silicone to the inside of the tank and the outside. Leave it to dry for 24 hours then conduct a leak test again using paper towels and clean water.

Can you fix a fish tank with silicone? ›

What do you do, though, if it begins to leak? Fix it with aquarium sealant! This isn't a difficult repair, and doing it yourself can save you a lot of money. You must be sure to use an aquarium glue that will hold up under water, generally silicone or an epoxy.

What is the best silicone to reseal an aquarium? ›

For the best aquarium safe silicone, turn to Loctite Clear Silicone Waterproof Sealant. This formula can be used in saltwater as well as freshwater aquariums. It's both flexible and gap filling, making it the perfect aquarium safe sealant for any tank with a capacity of up to 30 gallons.

Is silicone sealant harmful to fish? ›

As mentioned, any 100% silicone that doesn't contain mold/mildew additives is fine. Local hardware stores typically sell DAP brand and they have one product that is 100% silicone and labeled aquarium safe. ... Make sure you use silicone that does not have mold inhibitors in it.

How long does 100% silicone take to fully cure? ›

Silicone sealant generally cures within 24 hours. If it has been over 24 hours, check the silicone sealant “Use By” date on the package. If the product is older than the “Use by” date printed on the product, safely dispose of the product.

Is 12 hours enough for silicone to cure? ›

It's not recommended to expose the silicone to moisture before the caulk cures completely to ensure the caulk is completely waterproof. However, if you can't wait 24 hours, you should at least wait 12 hours. You can apply the caulk in the evening and wait overnight.

What can I use to seal my fish tank? ›

For the best aquarium safe silicone, turn to Loctite Clear Silicone Waterproof Sealant. This formula can be used in saltwater as well as freshwater aquariums.

How do I cover a leaking water tank? ›

Plastic Water Tank Leakage Solutions
  1. The first method is heating. This method works for small cracks that are visible from the top. ...
  2. Using fibreglass sheets can also help in preventing plastic leakage.
  3. You can also apply epoxy/putty to the affected areas.

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