# How to repair a leaking tank.



## AquaNeko (Jul 26, 2009)

I'm a bit foggy now as I can't remember everything the girl said when I was at BigAl's asking her how to repair a tank using aquarium silicone.

I think she said if the tank is old and not housing water at all over time the seals will dry out and thus that is how the water leaks in. She mentioned using a razorblade to take off old silicone then apply new silicone over top of it and wait 24hrs to cure then add water. 

I asked her if you should wait longer then 24hrs and she wasn't too sure on that but I think she said it would be out. 

1. Is this the correct way to reseal a tank?

2. Does the bonding get better if you let it cure longer then 24hrs?


I'm trying to avoid a Duece Bigalow.


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## ameekplec. (May 1, 2008)

I haven't done it before, but I'm about to reseal a tank I just bought because of the old silicone.

Anyways, the first step is to completely strip off all the silicone - use both a razor, then acetone to remove any residue - the acetone step is crucial to forming a proper seam. Residual silicone will interfere with the bond as once cured, silicone doesn't adhere to silicone.

The cure time depends on the type of silicone you get, but if it's just the stuff you grabbed at BA, 24 hours should be sufficient. 

Oh yeah, tape all your seams. Makes for a clean looking job.

BTW, how big is this tank you're resealing?


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## Darkblade48 (Jan 28, 2008)

I've resealed a leaking 30g before; it's not too hard, provided you have the patience. Proper tools will help immensely too.

As ameekplec mentioned, the first step is to strip all of the silicone off with a razor blade. Make sure you get every last bit. 

For the silicone itself, I would allow at least 48 hours to cure. There should be no hint of an acetic acid (vinegary) smell at all. Then, test fill the tank to test your handiwork.


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## AquaNeko (Jul 26, 2009)

ameekplec. said:


> I haven't done it before, but I'm about to reseal a tank I just bought because of the old silicone.
> 
> Anyways, the first step is to completely strip off all the silicone - use both a razor, then acetone to remove any residue - the acetone step is crucial to forming a proper seam. Residual silicone will interfere with the bond as once cured, silicone doesn't adhere to silicone.
> 
> ...


I'm still trying ot learn as much as I can about the items of aquaculture. I don't own a leaking tank (knock on wood) yet but while at BA's while looking at the wood the girl said I could put the wood into the tanks for my own reference of how it would look and then one thing lead to another when I was asking about aquarium silicone,toxic compounds, and then resealing tanks came up. Tape my seams?  I'm guessing with duct tape or electrical tape is all that comes to mind right now or aluminum duct tape to make it look better?    

Wow, I didn't know there was so many grade/choices to silicone for fish tanks. I was told this stuff does not adhere well to wood and rock. How many grades of silicone are there and what is the longest lasting and strongest ones out there and thier cure times? I got my aquarium silicone at Petsmart when I picked up some mealworms for Princess Toadstool and Peach. 

With aceatone umm.. do I need to do any special clean up to remove any of the chemicals used to disolve the silicone?


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## ameekplec. (May 1, 2008)

No, you don't need any chemicals to clean up acetone - it's very volatile so it'll just evaporate eventually. It helps to loosen and remove any remaining silicone residues, so once it's done it's thing, just let it sit out to dry. 
Also, clean all the seams you're going to silicone with acetone to make sure you remove any residues from handling, like the oils from your hands.

I have no idea how many grades/types of silicone there are. I was reading a huge build thread on RC (1000+gallons display) and they were using a grade of silicone that takes several weeks to cure. But apparently super strong!

haha, no, to make the tank look better you need speed holes, not tape.

The tape has the same function as when taping when painting - to get nice clean lines. Basically you tape off where you want the edge of the seam to end, then remove the tape (and excess silicone) before it cures.


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## conix67 (Jul 27, 2008)

Depends on the size of the tank, it may not even be worth re-sealing. Some are cheaper to buy a new, rather than going through hassles of resealing. The cost of material, effort and time is not worth to offset the cost of brand new tank, as the tank itself is usually relatively inexpensive in places like BA.


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## AquaNeko (Jul 26, 2009)

What would be considered a safe leak-test time? 24-48-72+ hours filled with water to make sure there are no leaks?


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## wtac (Mar 17, 2006)

It depends on where the leak is located, manner of leaking, age of the aquarium and it's volume. Other areas to look at is the condition of the silicone. If the inner bead is tough and stiff like "stale Jello", chances are that the silicone in the seam is reaching the end of it's useful bonding. If that's the case, it has to be completely dismantled, cleaned and reassembled.

The inner bead of silicone where it overlaps the two panes of glass offers next to zero structural strength but to seal hairline gaps in the seam to prevent leakage. It's the silicone _between_ the panes of glass that is basically holding it all together.

You are going to use a lot of single edged razors to scrape off residual silicone. Looking along the glass where you've scraped, like looking down the length of a piece of lumber to check to warps, you will see haze/streaks where there is residual silicone and keep scraping until it's all off. Using water will help lubricate the blade edge and using a blade holder will help with hand fatigue.

Acetone will not soften or really help in removing old silicone residue but is used to remove any oils from skin contact and prep the surface for a good adhesion of the new silicone.

A cure time of 24hrs is minimal and really depends on the thickness of glass to be "joined", bottom Euro-brace, dimensions, etc. Generally speaking for silicone cure time, GE 1200 is in the 24-48hr range and Dow 796(?) is 1-2weeks for a full cure depending on humidity and temp of the work area.

As conix mentioned, it's a time consuming undertaking to do it right. Depending on the "pickle" that you're in with the leaky aquarium, it's just cost and time effective to get a new one.

24-48hrs + 72hrs filled will be a good time frame 

HTH, JME/2C


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## Cory (May 2, 2008)

I was going to post almost exactly what Wilson posted (Wilson, I have to call you by the way, I picked up your message late) . You aren't going to have any issues with the tank falling apart, try to avoid piercing motions right where the panes of glass meet as you can puncture the structural silicone that way but otherwise you're safe. Razor blades work well, but I've found that a good paint stripper and different chisels work just as well without as much effort and strain. I've resealed several of my own tanks (actually have a 35 gal I've been putting off for an age lol) and quite a few for clients and really the only difficult part is the stripping. 

My tips for making the job easier would be:

1) Take the tank off the stand, put it on the ground and get comfortable. 

2) Make sure the tank is cleaned of dust, dirt etc. and completely dry before you begin.

3) Have a vacuum cleaner handy to vacuum up the discarded old silicone. You can do it by hand, but a vacuum ensures that all the little bits go too. 

4) Work in a pattern. Start at the top left corner for example, work your way down then go across the bottom pane towards the other corner and go up then to the other side across the bottom pane etc. Usually when you work a corner you loosen up the silicone on the adjoining section so it makes sense to keep going from there.

5) Take off the bulk of the silicone first then work on scraping the residual after. I find that it is easier to notice thin strips of silicone remaining on the glass. It is essential you get all of the old silicone off. 

6) Once you have the silicone off entirely, vacuum, then use a wet cloth especially along the corners to pick up any remaining silicone. Dry the area well then let it sit 24 hours. During this time you can use some rubbing alcohol to further clean the glass but I've skipped this step many times with no negative results. If the glass looks good it is, if you still see silicone you need to keep scraping. 

7) Use two sided tape along the inside edges to make nice straight lines. Leave .25" - .5" between the seam and the tape to make a good seal. Apply the silicone in a well ventilated area as the fumes can be nauseating (for me anyways) Apply a thick enough layer to be able to withstand some abrasion from rocks etc but not so thick as to be an eye sore. Run the silicone slowly and applying even pressure around the tank in a systematic fashion. Once you're done start removing the tape starting from where you first used silicone. If it is a larger tank you might have to start removing tape sooner. I find that if you remove the tape right away though sometimes a bit of what is on the tape drips and ruins the smooth look (which isnt a big deal on the bottom which will be covered but can be worse on the sides). 

All in all it's really not as difficult or daunting a task as most people think it is and it wont take you all day. I usually let silicone cure 48 hours before doing a wet test. 24 is supposed to be safe but 48 makes me feel safer.


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## Riceburner (Mar 14, 2008)

I resealed my 65G African tank. Basically what's been said already. 
I used GE Silicone I Window & Door in the blue tube from CTC. 
As long as it's does not say mold and mildew resistant.

















might look like this now...









I let it cure for 5 days and filled it with water out in the garage and let it sit for a week...not a drop lost.


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## gucci17 (Oct 11, 2007)

Useful tips but I strongly suggest people to be EXTRA careful when re-sealing tanks. OR like Conix mentioned, it may be better to buy a new tank. 

I don't mean to scare anyone but you have to watch the edges when you take off the trims. They are not sanded like the sides. There may also be splinters of glass (very hard to notice) when you are cutting silicone off the edges. Glass can cut you so quick and deep and you wouldn't even know. So please take your time and have someone else around if this is your first time resealing a tank. 

How do I know this? I used to build tanks for a manufacturer when I was a teenager. It's dangerous and you can really get hurt if you underestimate glass. I've seen guys get their fingers sliced open (among other things) by paper thin glass when trimmer excess silicon from edges. 

Anyways, back to the topic.

Cure times, varies...type of silicone, temp and humidity. Like Darkblade said, it shouldn't have the vineagar smell anymore. I give it more time than is needed when I reseal. Only because I'm not usually in a rush to use the tank. 72hrs is probably the generous concensus before you leak test.

I would follow Cory's tips on building a tank. It would seem easiest to use tape as guildlines for the silicone beads. I remember see a tank article that I wouldn't expect inexperienced tank builders to be able to free-hand a straight and even bead. 

Acetone was used to clean the tanks before being boxed up to give it the nice brand new tank shine. So for a one tank rebuild, I wouldn't bother going out of your way to find it if you have rubbing alcohol sitting at home already. Rubbing alcohol and a sharp razor should be enough to do the job of cleaning the surface. Just make sure you clean the surfaces you plan on applying silicone to really well or silicone will not adhear cleanly to the glass and will be more prone to future leaks.

Dont forget to tape the panels when you're done sealing the tank. It helps hold the front and back panels with a bit of pressure. Not too tight as it might squeeze out too much silicone from in between the panels. 

Goodluck and if you have any other questions just ask. I'll do my best to answer it...if I can remember lol


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## bigfishy (Jun 19, 2009)

gucci17 said:


> Useful tips but I strongly suggest people to be EXTRA careful when re-sealing tanks. OR like Conix mentioned, it may be better to buy a new tank.
> 
> I don't mean to scare anyone but you have to watch the edges when you take off the trims. They are not sanded like the sides. There may also be splinters of glass (very hard to notice) when you are cutting silicone off the edges. Glass can cut you so quick and deep and you wouldn't even know. So please take your time and have someone else around if this is your first time resealing a tank.
> 
> How do I know this? I used to build tanks for a manufacturer when I was a teenager. It's dangerous and you can really get hurt if you underestimate glass. I've seen guys get their fingers sliced open (among other things) by paper thin glass when trimmer excess silicon from edges.


SO TRUE!!!

I tried moved a 75G by myself and suddently the trim came off, and my thumb got slice by the edge! 

A very clean cut, (like a shark bite) blood squirt all over the driveway and the thumb quickly went numb! This is something that you don't want to experience!


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