How to Find a Leak in Your Fish Tank

A leaking fish tank in your home can be a worrying problem. In addition to causing water damage to your home, a leaking fish tank also threatens the health and livelihood of your fish and their aquatic environment. Leaks are often the result of simple damage to the seals of the aquarium. (Glass fish tanks are held together by a soft rubber sealant that prevents water from leaking out of the tank.) Fish tank sealants wear down over time or can become damaged from the sharp impacts of aquarium gravel or decorations. Finding and repairing leaks in your glass fish tank is simple if you know how.

Things You'll Need

  • Towel
  • Razor blade
  • Fish-safe silicone sealant
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Instructions

  1. Finding a Leak

    • 1

      Remove all fish and aquatic organisms to a temporary holding tank and take out all aquarium decorations and substrate. Having an empty aquarium will make the repair process much easier.

    • 2

      Move the aquarium to a level location in your home and place the aquarium on a solid stand. Set up bricks or cinder blocks if you do not have an aquarium stand. You can use any object that will not absorb water and that can support the weight of the fish tank with water above the ground.

    • 3

      Fill the aquarium half-full with water and carefully dry the outside of the tank with a towel.

    • 4

      Inspect the fish tank after allowing it to stand for 24 hours. If there are no leaks, fill the rest of the tank with water and allow it to stand for another 24 hours. This will help you determine whether the leak is on the bottom half of the tank, or the top.

    • 5

      Inspect the corners of the aquarium carefully for water. It is much easier to repair the leak once you identify which corner the leak is coming from, and if it is on the top or bottom half of the tank.

    Repairing a Leak

    • 6

      Scrape the existing leaky aquarium sealant off with a razor blade, and clean the area thoroughly with a towel and water to create a smooth surface.

    • 7

      Reseal the aquarium with a fish-safe silicone sealant. Apply a thick bead to the corners of the aquarium, and smooth the sealant by running your finger over the bead.

    • 8

      Let the silicone sealant dry according to its directions and retest the aquarium for leaks to ensure that the repair was successful. If not, repeat.