How to Fix a Crack in the Bottom of a Fish Tank

Fish tanks are made from panes of glass, and glass -- as we all know -- is relatively easily cracked. If the bottom of your fish tank gets a crack in it and begins leaking, there's no need to toss it. The repairs needed to get your tank up and running smoothly again are relatively simple and well within the capabilities of most aquarium owners. The most difficult part, in fact, may be finding a temporary home for your fish while repairs are made to the cracked tank.

Things You'll Need

  • Paper towels
  • Scouring pad
  • Rubbing alcohol (or vinegar)
  • Single-edge razor blade
  • 100% silicone sealant
  • Caulking gun
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Instructions

    • 1

      Transfer the fish to another container. Fill the container with as much of the water from your cracked tank as possible, and properly treat any added water to remove harmful chemicals. The water temperature in the new container should be the same as in the cracked tank.

    • 2

      Remove all of the water, gravel and other objects from the cracked tank and dry the tank completely with paper towels or cloth towels.

    • 3

      Scrub the cracked glass carefully with a scouring pad dipped in water, and then wipe the crack in the glass with a paper towel dipped in rubbing alcohol or vinegar to clean the glass thoroughly on either side of the crack so the sealant will stick properly to the glass.

    • 4

      Remove any old silicone if necessary with a single-edge razor blade and clean the area with rubbing alcohol or vinegar.

    • 5

      Run a bead of aquarium-safe silicone on top of the crack, and then rub a wet finger lightly over the silicone to press it down and make certain that it is well-adhered on both sides of the crack. Silicone will not stick to a finger if it is wet. Make certain that the silicone tube says it is safe for aquariums -- many brands designed for bathrooms contain a mildew-suppressant that is deadly to fish.

    • 6

      Clean the bottom side of the glass along the crack with rubbing alcohol or vinegar and run a bead of silicone on this side of the crack as well. Wipe your wet finger along the silicone to smooth it, and make certain it adheres properly on both sides of the crack.

    • 7

      Dry the silicone for a minimum of 48 hours (or according to the manufacturer's directions) before adding water and fish to the tank.