# Re-Sealing Silicone In Used Large Tank



## KingPygo (Jul 7, 2011)

So I finally picked up the 175 gallon bowfront from the LFS. The tank is just 3 years old, but it was saltwater tank before. The first thing I noticed was the worn silicone seams on one of the corners in the tank. It wasn't that bad, but just to have an ease of mind, I stripped it all off and started to run the new silicone up that corner. The next morning, I check on the tank and I noticed the joint which is the front pane to the side has small air lines. I know it wasn't there the day before. Does anyone know if this is safe? I already sealed the inside of the tank, the "airline" or whatever you call it is on the connecting joint between the front pane to the side.

I've attached a pics.

Thanks!








This is after I did the seams with clear silicone on the inside, while the oceanic is originally black. You can see the original black silicone which is the joint that you can see the air line? If that is what it is.








Here you can see the black silicone has the thin air lines.








This is how it looked for the other side of the seams, which I did not repair. You can see a slight blue line? Is that an airline or bubble too?








The tank itself, the far right is where the "Issue seam" is.


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## KingPygo (Jul 7, 2011)

^bump


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## Ægir (Jan 21, 2006)

Looks like the previous owner hit the silicone with a mag float or glass cleaner... I dont really see any major damage.

Putting more silicone over old silicone really does nothing... the two layers never adhere

If you are really worried, CAREFULLY remove the old silicone beads in the corners (NOT between the panels of glass, just the inside corner bead!) tape a straight line vertically 1/4" from the corner on both pieces of glass to get a straight finished edge. clean off all old silicone with razor blade, being careful not to gouge into the area between the glass. apply 1/4 inch wide bead of new silicone directly up the corner, and then with your finger (different fingers are different size, pick on that gives you the best radius in the corner, i personally use my ring finger or middle) and in one motion, wipe from bottom to top.

like this:





Just make sure you dont damage the areas between the glass, and you cover all areas.


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## KingPygo (Jul 7, 2011)

Ægir said:


> Looks like the previous owner hit the silicone with a mag float or glass cleaner... I dont really see any major damage.
> 
> Putting more silicone over old silicone really does nothing... the two layers never adhere
> 
> ...


Thanks man - but the issue is at the black silicone section not the clear. So you don't think the "air line" if that is what it is, is a problem? The pics are showing the black silicone where the joints connect between the front and side pane.


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## Ægir (Jan 21, 2006)

KingPygo said:


> Thanks man - but the issue is at the black silicone section not the clear. So you don't think the "air line" if that is what it is, is a problem? The pics are showing the black silicone where the joints connect between the front and side pane.


The seam isnt separated, and there's no air gap between the actual front and side panel. Its not uncommon for there to be small bubbles in silicone right out of the tube, and those are definitely small bubbles, not "leaks" or something to worry about.

Does the other corners feel dry? are they cracking or brittle?

If you are worried, take it in your garage our oudside somewhere level... and fill it up for a few days.


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## KingPygo (Jul 7, 2011)

Thanks man! Appreciates the advice. The rest of the silicone looks alright - the one on the right side looks a little damaged from rough glass cleaning, but looks okay. I don't want to do anything to it since it was holding water at the store. Id hate to add more unneccesary work. I'll fill it up and let it sit for a few days.

how many days do u think is safe to say its good to go?


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## Ægir (Jan 21, 2006)

If it holds for 24 hours its prob good... you will know the second its full if the seams are weak

Its really hard to say tho. ANY aquarium could blow a seam at any moment... you cant really predict it. I have seen brand new aquariums randomly blow out, and 15 year old aquariums that still hold water.


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## KingPygo (Jul 7, 2011)

so just checked the seams again this morning, looks like the other side has the same thing happening. But i didnt notice until i put a flashlight on it. It could be there the whole time and i didnt notice it. Could it be that the tank is empty and now the seams are easing up from the stress of water pushing out? I will fill the tank once my new silicone comes in. I'm getting the grainger silicone v108. something like that


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## MFNRyan (Mar 27, 2011)

So you got this tank used, the silicone in some of the corners had some damage to it, rough looking (but it held water at the store) so you decided to patch it an go over the old stuff with new silicone? Am I following this correctly?


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## KingPygo (Jul 7, 2011)

MFNRyan said:


> So you got this tank used, the silicone in some of the corners had some damage to it, rough looking (but it held water at the store) so you decided to patch it an go over the old stuff with new silicone? Am I following this correctly?


No - I purchased an 3 year old used tank. The corner seams appeared to be worn from rough cleaning (previously saltwater). So I decided to strip off the original black silicone and applied the new clear AGA silicone. My concern is at the joint where the front and side pane meets. The pics you can clearly distinguish the new clear silicone which is on the inside verses, the old manufacturer silicone which is black. THe only old silicone left is sitting in the joint which holds the front and side panes together.

My concern is the little bead that runs between the joints appear to have some air lines in them. It wasnt visible to me until I used a flashlight.

I was wondering if this is something I should be concern about based on its appearance.


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## MFNRyan (Mar 27, 2011)

Ok, how long did it sit with the old stuff stripped off an where did it sit, how level was it an was anything stacked against it or on it or anything like that


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## Ægir (Jan 21, 2006)

You are tripping man... quit messing with things and fill it up. If you sit and inspect things with a microscope you are obviously going to see small imperfections. In my opinion, the factory seals are way better off long term than your silicone patch job.

Here is a tank I got used, that was setup for over 2 years before, I had it almost 2 years, and now the current owner has had it over a year and a half after buffing tons of scratches out. It was a 155bowfront, it has been through far more than your tank, and still is in "good" condition seal wise, and i would trust it in my own place no doubt.

Notice how jagged the silicone edges look?









Here is a pic of my 40brdr that was a refugium... the snail eggs arent what im talking about, the bubbles down the ENTIRE seam.


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## KingPygo (Jul 7, 2011)

Ægir said:


> You are tripping man... quit messing with things and fill it up. If you sit and inspect things with a microscope you are obviously going to see small imperfections. In my opinion, the factory seals are way better off long term than your silicone patch job.
> 
> Here is a tank I got used, that was setup for over 2 years before, I had it almost 2 years, and now the current owner has had it over a year and a half after buffing tons of scratches out. It was a 155bowfront, it has been through far more than your tank, and still is in "good" condition seal wise, and i would trust it in my own place no doubt.
> 
> ...










Please hand this man a member of the month award now! Lol, thanks man, shows that you really care. Appreciates the sentiment. I will definately fill it up this weekend and keep you posted!


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## Smoke (Sep 8, 2010)

I think Aegir makes some good points. How bout we give it a test run (in a controlled environment) and see how it does?


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## jp80911 (Apr 3, 2008)

it's probably nothing too major, if you are concerned about it then place it to an area where you won't worry about water damage and fill the tank up. trace the bubble area with marker and leave the tank filled for as long as you feel comfortable and see if the bubble areas expanded, if yes then personally would just get an other tank but if nothing happened then you should be good to go.


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## Bawb2u (May 27, 2004)

KingPygo, I got your PM and looked over this thread as you asked. I feel that Aegir is giving you proper advice. I'd fill that tank and not think twice about it. Best of luck.


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## MFNRyan (Mar 27, 2011)

I think it's normal with age man. Checked my tanks over and one of them has a spot just like this one on the side. I wouldn't sweat it


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## Inflade (Mar 24, 2006)

when in doubt. fill the tank, and let it sit in the garage for a few days.

invest the time now and save the clean up later.

although i do agree, there doesnt seem to be anything of major concern here


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## KingPygo (Jul 7, 2011)

So I finally resealed one of the corners with Momentive RTV 103 black silicone - how long should we wait before we water test?


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## Sacrifice (Sep 24, 2006)

I would say at least 24 hrs, but the silicone tube should tell you cure time. Just make sure that you let it cure 100%.


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## Red Sox Fanatic (Jun 13, 2011)

Good LUCK!!


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## KingPygo (Jul 7, 2011)

So just a quick update - I've been tied up at work and stuff with the new house so I haven't had a chance to do anything with my tank until this morning.

So after hearing out what everyone has to say, I am comfortable with the seams and so called "Air lines". However, I wanted to remove the clear silicone work since I heard that Momentive RTV-103 is the best adhesive silicone which is strong than the silicone you find at the LFS and also the silicone work I did previously was sloppy.

My issue now is applying the silicone correctly and more neatly. If you look at the pics, it is not pretty at all~! THere are some gaps at the edges, of the seams. NOT in the connecting joint though. The stuff cures really fast and under 5 mins so I find myself not having enough time to evenly spread the silicone down evenly. I am trying to mimic the oceanic's thick seams and that requires more effort.

I'm thinking of re-doing it again but I would prefer not to and fill the tank soon! Id like to hear opinions about the current seam work etc.,

Thanks for all your help in this.


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## XiDiS (Aug 27, 2011)

I think it looks fine... with water and fish in there, no one is going to notice it


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## Ægir (Jan 21, 2006)

If you are struggling with the finish part, go to home depot or something and buy one of the "perfect caulk" things... it looks like you are blotting it instead of wiping in one motion from top to bottom.

It also looks like you are applying way too much from the get go...a 1/4" wide bead is prob plenty and you dont need a seam that wide. As I said before, a piece of tape on each side keeps it straight and neat looking, and also prevents the excess you scrape off from getting on the glass.


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