How Long Does Fish Tank Sealant Last?

How Long Does Fish Tank Sealant Last?

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If you’ve had your fish tank awhile or you recently bought a used one, you want to ensure it will stay intact without issue. Although you know the glass is good forever, you may wonder about the sealant holding the panes together.

So, what is the expected lifespan of fish tank sealant? Of course, this will depend on the ingredients of the sealant and its quality along with the age of the tank. But, as a basis for understanding, it should last for 10 to 15 years at the very least.

How long does aquarium caulk last?

Fish tank sealant is, essentially, silicone caulk. It’s a rubber compound material that bonds aquarium glass together. Brand new fish tanks or recently resealed aquariums shouldn’t present a problem. You can expect 20 to 30 years of use before it begins to breakdown.

If you are uncertain about this, expect 10 to 15 years to be on the safe side. However, you should inspect the sealant to see if there’s any peeling, discoloration, gaps or other areas where the bond doesn’t seem so strong. This will give you a better idea of the condition of the tank and if you will have to reseal it in the near future.

Will fish tank sealant eventually dry out?

Although silicone caulk requires drying to be effective, fish tank sealant won’t dry out. However, it does lose its bonding properties over time. This will be especially true if left in direct sunlight or the sealant comes into constant contact with the heater.

How can you quality check aquarium sealant?

In the event you plan on buying a previously-owned aquarium, ask the seller what they know about the tank and how old it is. Now, don’t expect an answer, but asking questions will save you hardship later on. Even if you do get an estimate on the tank’s age, you should check it prior to filling it with water and fish.

Run your fingernail along all the edges. Make note of any inconsistencies, unevenness, bubbles, peeling, curling or gaps. Also inspect the sealant for discoloration, mold, air pockets and slow leaks.

Can you repair damaged fish tank sealant?

So long as the tank doesn’t have any fish or water in it, you can remove the old, damaged sealant and put some new material on. You can reseal it yourself or take it to a professional. However, understand that you won’t be able to just add it over the old sealant because the caulk won’t stick well.   

If your tank’s ecosystem is well underway, you are going to have to set up a new tank, wait for the nitrogen cycle to establish and empty the damaged one before you can replace the sealant. This is because wet sealant will be caustic to your fish and destroy the water parameters, making for a dangerous environment to your aquatic life.


Fish tank sealants should last 20 to 30 years or more. However, if you have a used tank, expect the sealant’s lifespan to be somewhere in the ballpark of 10 to 15 years. When you plan on purchasing a previously-owned tank, try to find out if anyone resealed it in recent years.

Regardless of the answer you get, run your fingernail along all edges containing the silicone caulk to check. Pay particular attention for imperfections or other damage like profuse unevenness, discoloration, peeling, curling and bubbling. When in doubt, reseal it yourself or take it to a pro. Never put new silicone caulk on a tank that’s already full with water and fish.

See Also:
How Long Does a Fish Tank Filter Last?
Do Fish Tank Heaters Turn Off Automatically?
Can You Clean the Fish Tank Filter Cartridge?
How to Make Tap Water Safe for Saltwater Aquarium?