Seal that leaky fish tank!

How to fix a leaky fish tank with aquarium silicone

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.

Applying a bead of sealant on the inside of the tank will reinforce the strength of the seal once the water is applying pressure to the joint. Don’t skip the inner seal!

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.