# Sealing an old tank



## Tigercga (Mar 26, 2006)

I have a 180 gallon tank. Is it is worth the effort to reseal an old tank? Does NAFB good in reseal a tank? and how much would be the estimate cost to reseal a 180 gallon tank? 

Your comments are appreciated.


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## Riceburner (Mar 14, 2008)

Welll.....I resealed my 75G. If you don't want it, give it to me...I'll reseal it and use it.


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## gucci17 (Oct 11, 2007)

I would think a tank of that size would cost somewhere around $200 to reseal if not more.

In regards to whether or not it is worth resealing is totally up to you. If you have never resealed a tank, I don't recommend you starting with a 180 gallon tank unless you are totally confident in what you are doing. That's alot of water on the floor if something were to go wrong.

Where exactly is it leaking? If I were to reseal a tank your size, I would take the entire tank apart and start from scratch.


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## Tigercga (Mar 26, 2006)

It is not leaking, but the silicone is wearing off. I do not want to fill up water, then in the coming days it starts leaking.


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## gucci17 (Oct 11, 2007)

If the glass is in good condition then it'll be worthwhile to have a professional to reseal the tank. Better safe than sorry


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## Riceburner (Mar 14, 2008)

Completely clean away the interior silicone, not the stuff between the glass, just the corners. Reseal the corners. Let cure for a week(that's more than needed). Test fill for a week.


...course, since it's a 180....can't hurt to have a pro do it.


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## gucci17 (Oct 11, 2007)

Riceburner said:


> Completely clean away the interior silicone, not the stuff between the glass, just the corners. Reseal the corners. Let cure for a week(that's more than needed). Test fill for a week.
> 
> ...course, since it's a 180....can't hurt to have a pro do it.


I can't recommend that on a 180 gallon tank. Pressure is too great to just take the chance on resealing the corners. You are merely applying a bandage to the leak.


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## BillD (Jun 5, 2006)

Since the tank doesn't leak, there is no danger in a reseal. Even if it did leak, it wouldn't necessarily need a dismantling, regardless of the size of the tank. In some ways a large tank is easier to do than a small one. Access is easier although you need to work quicker to get it all in before it starts to set. All the work in a reseal is in the preparation. Removing the old silicone can be a tedious job, but once done, applying the silicone is fairly easy. If you aren't comfortable applying a caulk, you can buy some cheap caulk and practise on some cardboard boxes.
The inner fillet seal is just insurance against leakage. A properly assembled tank will hold water without the inner seal. It doesn't really offer any extra strength, but, will seal any small voids left during the assembly. I don't really know what you mean when you say the inner seal is wearing out, so I can't say whether it is even necessary.
The only risk here is that if there are voids, and the reseal is not done correctly it may leak when you are done. However, it is well worth the effort, especially on a tank that size. Most of the tanks I own are former leakers I repaired.
As a point of reference, the first tank I ever built, circa 1965 or 66 is still in use, even though the silicone application between the panes is not that great. Also, there is no more pressure on that tank than on a 90, which uses thinner glass and has less bonding surface between the panes.


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## ryno1974 (Dec 6, 2009)

Agree with Bill. All the tank needs is the insides seams redone. There is no real challenge in doing this, just patience. Clean off all the old silicone with a razor blade, making sure to not dig into the seam between the panes of glass. When you think you are done, do it two more times. Then you only have one more time to go. Once it is clean, apply masking tape about 1/2" from each edge, creating a clean edge for the silicone. Apply a bead in each corner, and spread it smooth using your finger or a tool designed for the task (I use my finger and it works fine). As soon as you are done smoothing it out,pull off the tape, leaving a nice clean line of silicone. Let sit for about a week, and test fill it.

No need for a pro, just $4 for silicone, and $3 for a roll of tape 

Good luck, let us know how it goes.


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## gucci17 (Oct 11, 2007)

Honestly, I can't recommend it. As 'easy' as it is, you have to remember it's your floor that the water ends up on. You're not going to be able to blame the people in this forum either. 

I've worked for a tank manufacturer and trust me, it's not just cutting out silicone and running a new bead on. 

Good luck


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## BillD (Jun 5, 2006)

gucci17 said:


> Honestly, I can't recommend it. As 'easy' as it is, you have to remember it's your floor that the water ends up on. You're not going to be able to blame the people in this forum either.
> 
> I've worked for a tank manufacturer and trust me, it's not just cutting out silicone and running a new bead on.
> 
> Good luck


I wish I had known that before I built my 6 tanks and sealed the other nine. Fact of the matter is that you can have a leak with a brand new tank. That is how I got most of my tanks. They were returned to the store because they leaked. I bought them and resealed them.


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## ryno1974 (Dec 6, 2009)

gucci17 said:


> Honestly, I can't recommend it. As 'easy' as it is, you have to remember it's your floor that the water ends up on. You're not going to be able to blame the people in this forum either.
> 
> I've worked for a tank manufacturer and trust me, it's not just cutting out silicone and running a new bead on.
> 
> Good luck


Well,then we agree to disagree. Much like Bill, all but one of my tanks have been leakers / broken / resealed and I have never had a leak. I dont have the experience he has, but I do have years with no leaks on a repaired tank.

As someone already mentioned if you dont want to risk it let me know and I will take it off your hands for you.


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## kev416 (Aug 22, 2010)

If a larger new tank leaks there's a good chance the construction seal (the seal between the glass) is at fault. That would require taking off the bottom trim and examining it if leaking from the bottom or examining the sides closely if leaking along the side seams. If the construction seal is faulty you will see it. It appears cloudy. When the tank was constructed the glass was dirty or the pneumatic silicone gun ran out of silicone and the silicone bead too thin. You have to remove the pane or deconstruct the tank. I have been given many large tanks that have this fault. It's not as simple as resealing the water seal. If the tank is old (hand made in the eighties) often an air bubble caused the leak after the inner silicone water seal wore away. It's rather a simple fix by resealing. Newer tanks don't have these air bubbles. In the case of a 180 gallon that doesn't leak I'd trust that the construction of the tank is fine and I would reseal it before refilling. Use a good silicone like GE SCS1200. The cheaper stuff sold at the Big Box stores doesn't cure that well. You need a construction silicone.


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## loonie (Mar 29, 2008)

Re sealing a tank is not a big problem. Just like what Bill said, anyway we all learn by doing it. Its best as adviced you use the GE1200 silicone, it is not avail in Home Depot or Canadian Tire but you can still find it in some stores.


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## gucci17 (Oct 11, 2007)

BillD said:


> I wish I had known that before I built my 6 tanks and sealed the other nine. Fact of the matter is that you can have a leak with a brand new tank. That is how I got most of my tanks. They were returned to the store because they leaked. I bought them and resealed them.


I'm glad it worked out for you and your 15 tanks. I'm just expressing my opinion and personal experience having worked at one of the main tank mfgs in Ontario. I'm not here to argue but just trying to inform the OP that things could go wrong. Would you be the first one to step up and take ownership on damages that occur if somehow the tank did leak after the OP took your advice?

Of course a brand new tank can leak, no one said it had to be an old tank.



ryno1974 said:


> Well,then we agree to disagree. Much like Bill, all but one of my tanks have been leakers / broken / resealed and I have never had a leak. I dont have the experience he has, but I do have years with no leaks on a repaired tank.
> 
> As someone already mentioned if you dont want to risk it let me know and I will take it off your hands for you.


I never said it's impossible to have a leak free tank after being resealed. If there has been a leak, it means the silicone between the panes of glass has been compromised. All you have done is applied a layer of silicone over it which could still wear out of accidentally dug into when doing maintenance and leak again. That is very unlikely though but hey, it could happen.


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## kev416 (Aug 22, 2010)

One thing to mention. When removing the old silicone don't score the glass with a utility blade or single sided razor when attempting to remove the old silicone. Take your time. Start on the glass pane that slips under the other. There's a remote chance a crack or concoidal fracture may form especially when moving it or dropping it on a stand to avoid squished fingers.


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