Should I Reseal My Aquarium?

The short answer is no.  Repairing the silicone seal on an aquarium is a recipe for disaster. It’s rarely as cost-effective or safe as a replacement aquarium.


The amount of work to correctly repair the silicone seal is almost never worth your time and suffering.  Unless you have a lot of patience and the correct supplies, resealing aquariums is best left to the professionals.  As someone that attempted to reseal a used tank and ended up with 220 gallons of saltwater on the floor… I may know a bit on the topic.

Some Info About Silicone Adhesives

Silicone is an amazing material and has been holding glass aquariums of all shapes and sizes together for ages.  We use silicone on our aquariums because it’s durable, waterproof and mostly inert once it cures.


That last part about being inert is the key factor. This means that cured silicone will refuse to bond with almost any substance, including fresh silicone.  Cured silicone’s ability to repel things from sticking to it is probably only surpassed by Teflon.  Think of it like trying to force two similar magnets together.

Why Does This Matter?

This means that you must remove 100% of the existing silicone that is currently holding your aquarium together.  Any old silicone that is left behind will create micro-gaps between your new adhesive seal and the glass of the tank.  Even the tiniest of gaps will expand and cause the entire tank to fail over time.

It Can’t Be THAT Difficult, Right?

There is more to it than grabbing a razor blade and scraping the glass clean.  Aquarium glass does not fit seamlessly together because the corners will have tiny gaps.  Even with the smallest 1/32 or 1/16 inch gap between the panels, a gap is still a gap.  This means that the original silicone is actually filling that gap as well as forming the visible L-shaped corner seal.  How are you going to remove the silicone from inside the gaps?

This is what people think the seal looks like...
This is what it REALLY looks like. Notice the gap?

How to Correctly Reseal an Aquarium

The cost of hiring a professional to repair the silicone seal on your tank may give you sticker shock.  I can assure you that there is a very good reason why their prices aren’t in the bargain basement realm.

Prep Work

After scraping off all of the visible silicone, the gaps will still need to be cleaned.  This is done by removing the top and bottom plastic trim pieces on the tank.  These trim pieces were never made to be removed.  That means they will most likely sustain damage and need to be replaced.  Once the trim is removed, the panels will need to be split apart.

You read that right…  To correctly prep a tank you will need to break it down into a pile of glass panels.  Once that is done, the remaining silicone must be removed from the edges with sandpaper or a light grinding wheel.



Now, you have a pile of glass panels with 100% of the silicone removed.  Hopefully, you were able to buy the correct plastic trim pieces to fit your panels.  If the trim does not hold the corners tight enough they will probably blow out from the pressure.

Let’s assume you were able to find the correct trim pieces for this example.  You will then have to rearrange the panels in the trim and apply your fresh bead of silicone.  All of that annoying prep work ends with a few lines of silicone that you quickly smooth with your finger. Crazy, isn’t it?


Drying & Cure Time

Cure time will vary depending on the size of the tank and the thickness of the glass.  A complete cure could take a few days or even a few weeks and this is not a step you want to rush.  Rushing the curing of your new silicone seal will be like heading directly to jail, do not pass go, do not collect $200. Happy scraping and grinding while you redo everything!


Leak Testing

Once the silicone is completely dry and cured, you should fill the newly sealed aquarium with water and let it sit for a week.  You do have a place that will be fine if it gets completely flooded by a blown out aquarium, don’t you?

This step can be tricky.  When I resealed that 220 gallon aquarium, I leak tested it for 2 weeks.  It seemed perfect, so I installed it in my basement and added 2 tiny green Chromis fish as pioneers in a brave new world.  I received a call at work about 3 days later that the bottom back seam was leaking!  I guess those two fish needed to go on a diet, but who knows?

Almost half the water was on my floor by the time I got home.  Here is something that I guarantee you have not thought about… where you do store 100ish gallons of freshly mixed saltwater from a leaky tank?


Not only did I have a blown out tank and a flood, but I had to basically pour an entire case of reef salt down the drain.  I was able to save the fish and move them back to another tank, but the drywall in my basement wasn’t so lucky.  Drywall is lined with paper and while the front of the wall is protected with paint, the back of the drywall will get covered in mold.  Still thinking you can save money by resealing your own aquarium?

This what the back of your walls will look like!

So... Where Did I Go Wrong?

I didn’t have anyone to tell me about the need to disassemble the panels and grind them clean.  I used a razor blade and just dug out everything I possibly could from between the panels.  I figured that a nice bead on the surface of the glass would hold it together.  I didn’t understand that the new silicone inside the gap was being repelled by the old silicone that I wasn’t able to dig out.  This put uneven pressure on the joint and caused the bottom seam to fail.  It was a costly lesson, but maybe this article will help you learn from my mistakes.

The smallest amount of old silicone can ruin your seal

When Does Repairing the Silicone Make Sense?

If you have a very large aquarium that was custom built it might make sense to have it resealed.  However, newer tanks may offer better features that still make resealing a poor choice.  A quality silicone seal should last at least 10 years.  A lot of upgrades in overflow boxes and drains can happen in 10 years.  Whatever you do, hire a pro or prepare for a lot of different work and make sure the flood insurance is all paid up.

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Phil Beauregard

Phil Beauregard

A man with a beard, that you can trust! Phil Beauregard is a business consultant and entrepreneur that has been addicted to fish keeping since childhood. He grew up with stories of his grandfather’s exploits during the early days of reef aquariums and African Cichlid breeding. Phil brings a flair for high tech DIY projects and his love of teaching others to the reefing community.

1 thought on “Should I Reseal My Aquarium?”

  1. 100% correct! Resealing a aquarium is a labor of love. I am not a professional at all. I have successfully resealed several aquariums, mostly 55 gallon and one 46 gallon bowfront. I am a third generation tanker, been at it over 35 years. The main thing is a CLEAN surface,no residue of anything on any edge’s. Everything most be wiped down several times with acetone, every edge, every surface where silicone will be applied. Plan on atleast a week each side and such for the bottom. Love of the hobby ,great patience, and a lot of tenacity, can result in a positive outcome.

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