How to Repair Cracked Aquarium Glass?

There is nothing more exasperating for an aquarist than finding a crack in the aquarium glass. Often, minor cracks go unnoticed till they start spreading and even cause the aquarium to leak in some cases.

Cracks in aquarium glass are more common than you would think, especially if there are children around who like to tap on the glass frequently to get the attention of the fish (I did this a lot when I was a child and I still do it sometimes).

Fortunately, it isn’t too difficult to fix a cracked aquarium glass.

With the right tools, you can repair it in no time and the glass will be as good as new.

Steps to Repair a Major Crack or a Leaky Aquarium Glass

A cracked aquarium glass may cause major issues if it is not fixed in a timely manner. You might find yourself facing even bigger problems if you have a large aquarium.

The pressure of the major crack may result in leakage as well and there will be a large puddle of water on the floor for you to constantly clean up.

If the crack is severe or if it starts leaking, it can even cause the aquarium to break which will result in more damage. Here are the steps to repair cracked aquarium glass:

Step 1: Prepare the Surface

Start by draining out a small amount of water so that the water level is low enough to provide you room to properly clean and dry the cracked area. You can do this by using a container, a bucket, or a cup.

In case the crack is at the bottom of the aquarium, you’ll have to empty out the entire aquarium. Transfer the fishes, plants, and decorations in your backup aquarium while you fix the glass.

Remember that you will have to wait for the sealant to properly dry up before you can refill and restore the aquarium. Therefore, ensure you have a proper plan to maintain the health of your live plants and fishes for the time being.

Step 2: Remove the Old Sealant

The old sealant must be scraped off using a razor blade scraper. Be sure to only remove the silicone from near the cracked or leaky area and not from between the glass panels.

Be careful when removing the old sealant if the aquarium is still filled. Avoid letting any residue of the old sealant from dropping in the tank.

In some cases, the old silicone doesn’t bond well with the new sealant. You might have to remove more silicone from the tank and reseal it.

Step 3: Clean Up the Spot

Use a clean towel to wipe the area and then dampen it up with a small amount of acetone. Wipe again to eliminate any residue or foreign material from the cracked area. Use a paper towel to dry up the area and then let it air dry for around 15 minutes.

Cleaning the area first is required as this will ensure the new sealant can properly stick to the glass and to reduce the chances of any future leaks.

Step 4: Seal the Area

Use a 100% nontoxic silicone sealant to seal up the cracked or leaky spot. Use a caulking gun along the cracked area running along with a silicone bead.

Afterward, smoothen it out using a caulking tool or a damp finger so that it covers the cracks or the leak thoroughly.

It is recommended to use a 100% silicone and non-toxic sealant to protect the health of your fishes and live plants. You must make sure that there is absolutely no fungicide present in the sealant as this will harm the habitats of the aquarium.

It would be tempting to repair the crack from the outside of the aquarium but it is far more effective if you seal it in from the inside.

Repairing the crack from the inside will hold it more efficiently since the pressure from the water will tighten up the seal. If you apply the sealant from the outside then the pressure of the water will push away the silicone from the glass.

Step 5: Dry the Sealant

Give it at least 24 hours for the sealant to completely dry up. It is ideal to leave it for almost 48 hours, especially if you apply it in a dry and cool environment. This will ensure that the sealant is dried and set properly.

You can also use a portable heat source like a heat lamp to escalate the sealant to properly get sealed up. However, make sure that the heat is not more than 110° degrees Fahrenheit.

Step 6: Monitor the Repair

To make sure that you have successfully repaired the crack, monitor the aquarium for a few hours before you fill it back up.

Inspect all the glass panes for more cracks or leaks. Refill half of the aquarium with water and monitor the progress. After a few hours, fill up the whole tank with water and monitor again to ensure there aren’t any leaks.

Examine the recently repaired area to make sure that the water pressure hasn’t loosened up the sealant.

You can do this by putting up a clean paper towel with tape and leave it on for at least two hours. If the paper is dry, this indicates the crack has been fixed.

Step 7: Restore the Tank

Once you are sure that the glass has been fixed, you can start restoring your aquarium. Be sure to clean the plants and another décor before placing it back inside. Add in the gravel first and then other rocks and objects you have to place on the floor of the aquarium.

If you need to add in some chemicals for nutrients then do this before placing back the live plants. Once everything has been set up in the aquarium, carefully transfer back the fishes from your backup aquarium.

Repairing a cracked aquarium glass is a good opportunity to do some cleaning of the aquarium and decoration. Make sure you clean up everything properly before placing it back in.

Related Article: How to Clean Aquarium Sand?

Cleaning Tips for Aquarium Glass

To maintain the cleanliness of the aquarium glass, you must clean it from both inside and outside.

There are different methods of cleaning either side of the aquarium glass.

Glass Cleaning from Outside

Cleaning the glass from the outside is pretty simple. Here are some tips:

  • Always dampen the paper towel or soft cloth with warm water to wipe the glass
  • Cleaning the glass with newspapers is also super effective
  • Avoid using chemical spray cleaners anywhere near the aquarium as the airborne residue can enter the water and affect the habitats
  • To prevent hard water crystals, soaking the paper towel or cloth in warm water can help
  • If you have an acrylic tank, make sure you clean it using the cleaning solution especially intended for the acrylic tank.

Glass Cleaning from Inside

Cleaning the inside of the aquarium glass takes more effort than cleaning the outside, but it is still pretty simple. Here are two methods to do it:

  • Using Sponge – For regular cleaning, the sponge method is the best. Just remove the cover of the aquarium, and gently place the sponge in the water to avoid disturbing the fishes too much. Use up and down hand movements to wipe the glass. This will remove any algae or other stains. Never use soap or other liquids.
  • Using Magnet – A magnet aquarium cleaner is another effective cleaning option. Remove the cover of the tank and place the half magnet on the inside. The cleaning pad should face the glass. Then, immediately place the other half of the magnet on the outside facing the magnet inside. The two magnets will hold each other up. Guide the magnet up and down to clean the inside.
  • Algae Scraper – In case the algae formation is tough and the above two methods don’t get rid of all of it; an algae scraper will be useful. Select the right attachment and scrub the algae to loosen it up. Use gentle movements to avoid stressing out the fishes and to avoid water splotches all over the floor.

Regular cleaning will also help in detecting any cracks or leaks in time before the problem gets worse.

If the crack is really bad and has started leaking, it is better to remove the cracked or damaged glass pane and replace it with a new one. All you need to do is measure the glass pane properly to get the right fitting.

Remove the glass pane yourself only if you have the right tools or ask a professional to do it for you. Ensure the sharp edges are buffed to avoid any injuries.

Once the new glass panel has been installed, you can restore the aquarium as before. Make sure you clean it thoroughly first to eliminate any broken glass residue from inside to ensure the safety of your fishes.

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