- 1). Remove fish from your damaged aquarium and transfer them to a well-oxygenated temporary tank. Remove all accessories so the aquarium is bare.
- 2). Thoroughly dry the aquarium, locate the crack and then carefully align the glass so that both sides of the crack are flush with one another.
- 3). Tape one side of the crack with masking tape to hold the glass in place.
- 4). Apply a thick bead of aquarium-safe silicone to the un-taped side of the crack. Only use clear silicone sealants and always check to ensure that there are no mildew-inhibiting chemicals in the silicone mix, as they are toxic to fish. Most aquarium-safe sealants will clearly state that they are fish-friendly on the label.
- 5). Use the putty knife to help smooth the silicone over the crack to provide a solid seal and help stabilize the glass. Though it may not be aesthetically appealing, it is best to have a solid, thick seal on the tank to ensure that the crack does not reopen in the future.
- 6). Allow the silicone sealant to dry according to the recommended time on the instructions and then remove the tape on the opposite side of the crack and repeat the process.
- 7). Remove unwanted excess silicone by razor blade once dried.
- 8). Fill the repaired aquarium and ensure that the silicone seal is complete and that no further leaks develop before reassembling your fish tank.