# Fixing a leak on the seam of the tank.



## sciencefiction (27 Aug 2013)

Hi guys. Unfortunately my 5f tank was pouring water out today. Fortunately it turned out the leak is on the seam near the top of the tank so I was able to stop the leak by draining the tank a few inches.

The problem is I just don't want to drain that tank and reseal because it's massive and I've nowhere to put my 50 fishes and all plants, soil and sand.

So my question is, is there anyway I can easily fix that, providing that the leak comes from the silicone itself. The silicone is actually about a cm thick and is between the glass sides themselves, not just inside. Please see the black silicone on the picture. The part leaking is where the black silicone on the picture is slightly thinner just above the water level.







I wanted to ask, has anyone heard of the CT1 sealant? Here is a link and some info about it I got from that website.

http://www.ct1ltd.co...s-with-ct1.html

*Well CT1 is not a silicone sealant but unique hybrid polymer formulation that is able to stick onto wet surfaces even under water making it the perfect sealant for sealing fish ponds, CT1 contains no solvents and is 100% V.O.C free so will not contaminate the water extremely fish friendly. There have been occasions when the fish have nibbled at the cured CT1 sealant with no adverse effect but with so many species of fish we cannot say that for all species.*


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## Andy Thurston (27 Aug 2013)

I bought some aquatic sealant that could be used with the tank still full it was £mega though


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## sciencefiction (27 Aug 2013)

Well, I have some aquarium silicone but it's dried out so I have to buy something. I am just not sure what to do. I think to purchase the CT1 above as it seems to work fairly well and fast from watching youtube videos and I don't need to dry out the part to be sealed. They've got different colours including a totally transparent one like glass, not whitish like the normal silicone. I wonder if applying on the inside and outside of the leak part would do?


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## foxfish (27 Aug 2013)

I would be concerned as to why you have a leak, I assume the leak is new?
If that is the case something must be moving or deteriorating.
Silicone is a structural glue that offers immense lateral strength  so I would consider a small, say 50mm corner brace  silconed in place as well as a bead of silicone over the leak.


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## Andy Thurston (27 Aug 2013)

Id be looking for a new tank. I wouldnt trust the rest of the seams to hold at the very least as foxfish says  some sort of extra strength down the entire length of seams the last thing you want is all your fish on the floor if it fails in a big way and the entire side comes off.


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## sciencefiction (27 Aug 2013)

Yes, foxfish. That's a concern and it's a new leak. I only had this tank since January this year.
The tank is very old, possibly 7-8 years and I have no idea what had happened to it in the past. After looking very closely at it I think the part where the leak comes from has been fixed before from the outside as there's a rough piece of silicone over the old one. I checked all the other silicone and it's totally smooth like a manufacturer's job but this part has a rough patch line over the smooth one. If it's not that, then one day I'll wake up to worse stuff.

This is the only 2nd hand tank I ever got and I already have problems with it.


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## sciencefiction (27 Aug 2013)

Big clown said:


> Id be looking for a new tank. I wouldnt trust the rest of the seams to hold at the very least as foxfish says some sort of extra strength down the entire length of seams the last thing you want is all your fish on the floor if it fails in a big way and the entire side comes off.


 
Oh, god...I just don't have the money now at all. But that's totally possible and I am dreading it.


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## Andy Thurston (27 Aug 2013)

You could strip the tank and rebuild it with the product you mentioned earlier but it dosent help with a temporary home for flora and fauna


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## sciencefiction (27 Aug 2013)

Big clown said:


> You could strip the tank and rebuild it with the product you mentioned earlier but it dosent help with a temporary home for flora and fauna


 
I wouldn't trust myself doing that at all. I am trying to think what to do. It's horrible and the tank was going great inside.

Do you all think it's likely the silicone all along the seam will give way if it's started? I know I am clutching on straws here.


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## foxfish (27 Aug 2013)

It is always difficult to give advice from a far ... I wish I could see the tank & help you make a decision...
Are there braces in place at the moment or is the tank a brace less model?


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## sciencefiction (27 Aug 2013)

Thanks foxfish.
The tank is braceless/rimless altogether, so worse scenario I guess as all it's held by is the silicone. That's the way the model is.
The silicone part where the leak is, is visibly thinner, like missing some of the silicone. See on the above picture where the plant roots are pointing at the silicone to the right side, that's the leak.....I just can't imagine how that happened and since it's a 2nd hand, it may as well have been like that from the start but I didn't pay proper attention when inspecting it. But I am totally not certain because I don't remember noticing anything, and it took around 5 months for it to leak.
What I am afraid is if it's the stand somehow giving way as it's old too. But it's the original stand that came with the tank.


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## Andy Thurston (27 Aug 2013)

Are there similar repairs on the other corners. Is it possible that the tank has had braces removes which caused the original leak and subsequent repair. Does the rest of the silicone look sound, are any other bits that look dodgy/starting to come away from the glass


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## sciencefiction (27 Aug 2013)

Here is a better picture of the leak. You can see the see the wider transparent area in the black silicone where the leak is to the righ side of the picture(corner of the tank). The black is the silicone and then the greyish is the glass with is 10mm thick.


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## foxfish (27 Aug 2013)

OK I would suggest that you fit some corner braces like the ones on my tank, I had them cut from 120mm squares of 10mm float glass & silicone them in.


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## ian_m (27 Aug 2013)

Tearing of tank seams, especially at the top is can be due to the tank being placed on non flat surface. This causes twisting of the glass panes, causing silicone tearing at adjacent corners ie two adjacent corners are under compression and two under tension, the tension ones tearing.

My mate had a tank on a sideboard and the sideboard started deforming under weight of the tank. It was first noticed as a slight leak on front top right of tank. When drained down and moved there was a matching leak on top rear left of tank as well. Placing the empty tank on the sideboard revealed the top of sideboard was not longer flat having "dropped" due to leg collapsing on front right, causing bowing of the sideboard top. He removed (or glass shop did) & replaced the two silicone seams, built a proper tank stand (lots of 2x2), that was about 15years ago and tank is still going.

Or could just be poor silicone.


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## sciencefiction (27 Aug 2013)

Big clown said:


> Are there similar repairs on the other corners. Is it possible that the tank has had braces removes which caused the original leak and subsequent repair. Does the rest of the silicone look sound, are any other bits that look dodgy/starting to come away from the glass


 
Not that I can see. It's just this corner area. Who knows if it has braces or not, but at the moment it doesn't have anywhere, including the bottom. It's an old Aquael tank model.


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## sciencefiction (27 Aug 2013)

ian_m said:


> Tearing of tank seams, especially at the top is can be due to the tank being placed on non flat surface. This causes twisting of the glass panes, causing silicone tearing at adjacent corners ie two adjacent corners are under compression and two under tension, the tension ones tearing.
> 
> My mate had a tank on a sideboard and the sideboard started deforming under weight of the tank. It was first noticed as a slight leak on front top right of tank. When drained down and moved there was a matching leak on top rear left of tank as well. Placing the empty tank on the sideboard revealed the top of sideboard was not longer flat having "dropped" due to leg collapsing on front right, causing bowing of the sideboard top. He removed (or glass shop did) & replaced the two silicone seams, built a proper tank stand (lots of 2x2), that was about 15years ago and tank is still going.
> 
> Or could just be poor silicone.


 
Thanks Ian. So whatever I do, I need to get the fish and everything out of there. I can't be sure about that stand not being the problem, or the little legs beneath the bottom board, or I don't know.
Oh, my gosh. I wish that's not happening to me right now.


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## ian_m (27 Aug 2013)

Same mate also broke a small tank he was given by not putting down any "sheeting" under the tank. Just placed the tank on kitchen work top and couple of weeks after filling noticed water leaking out. Traced to a small lump of gravel under tank breaking the bottom pane. Leant lesson why sheet of 3mm polystyrene is needed.


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## sciencefiction (27 Aug 2013)

I checked the base putting the tank and the tank has a sheet of polythelene underneath as it's flat base, old style.


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## sciencefiction (28 Aug 2013)

So I am going to have to patch the tank for now and prey it lasts for another while without making a swimming pool out of my place until I can afford to buy a new tank and stand. I still think it's possible that silicon gave way with the previous owner once before because I can see the extra line of silicone applied to this side on the outside over the old smooth one and being on the outside I was reading the water pressure can push it out again. So I'll try patching both inside and outside now.

If I have to empty the tank to test the stand and all for twisting and damage I'll be just getting rid of everything.
I checked online and it seems that's the way these tanks were made years ago, no braces but the bottom glass of my tank is extra thick 20mm, the sides 10mm. I ordered the CT1 sealant and try it on a partiallly full tank. If I have to put braces on top to give extra support I'll have to get rid of all my emersed tropical plants and I'd rather just sell everything and hope one day I can afford a larger rimless tank design.


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## ian_m (28 Aug 2013)

Sounds like issues from previous owner rather than you "breaking it". So no reason to not fix it.

Put some cling film/polythene on water surface along with kitchen towel to catch any rubbish whilst you work.
Cut out, with craft knife as much failed silicone as possible.
Dry the area to patch.
Clean if possible with either meths or IPA alcohol.
Try opening the gap slightly with say match stick, don't use metal object as might crack the glass.
Apply masking tape along edges of seam where you DONT want silicone.
Apply silicone. Smooth gently with finger or shaped piece of wood or silicone shapers. Otto-Chemie Fugenboy Sealant Tooling Set Blue (Small) - Otto-Chemie Mastic Sealants Adhesives & Tools - Mastic Sealant & Waterproofing Manufacturers - Product List - Sealants Online
Remove masking tape.
Leave 24 hours.
Fill with water.
Sit back and admire tank and handy work.


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## sciencefiction (29 Aug 2013)

I've been reading, reading, reading about that and I have decided to take the plunge and empty the tank and check everything. It's the cheapest option as I can barely afford to pay for plastic containers, silicone, etc...., not to mind a new tank anysoon in the future. The tank is currently half full at the moment until I can move everything out the weekend possibly. I hope it lasts till then.

Then once all empty including the substrate, I'll move away the tank, check the stand and tank of course. I'll make sure the stand is level and it hasn't slipped or anything. The stand is on a carpet.
Then how do I go about resealing the entire seam on that side/corner? Should I cut out the old one from top down to a level, or what's the safest way to do it? I read that's a structural leak, meaning it's not just a pin hole, but an  line/section of the seam so I need proper repair and resealing? Too bad I bought the clear colour of the CT1 and the old silicone is black  I haven't received it yet, so I may not be able to reseal the tank till next week.

My fish will live in plastic containers for a a good while until everything is ready and I am sure I can put all stuff back. I am dreading all possibilities that may arise, for example if the stand has failed somewhere and I can't put the tank back at all as I can't buy a new stand at the moment.  It's the worst time of my life for that to happen. It took me a good while to save for this tank and all it needed to run it the way I wanted, now it's flaming useless  and I can't buy another.


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## sciencefiction (19 Sep 2013)

Well, just an update. I still haven't fixed the tank. It has been running half full for 2-3 weeks now. The reason being something happened with my sealent order and the first one didn't arrive at all, so they had to resend another one. I finally got it this afternoon. I won't be able to start emptying the tank until the weekened.
My fish are visibly suffering. I got two dead fish for this period. Many of the plants melted for whatsoever reason. Some of them are barely getting any light because they got overshadowed completely with the lower water level.


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## sciencefiction (24 Sep 2013)

Well, the tank has been "kind of fixed" for the moment. We'll see for how long. We did not empty it at the end. The stand has some wear and tear damage although it should hold for another while.  The corner where the leak is had kind of sank causing a twist, it must be the floor as well and that was not there when we initially levelled the tank. So we figured this was the reason for the damaged seal. Maybe the tank slipped or we unlevelled the tank as I remember we had to slightly push it more towards the wall at some stage and we may have created the problem then.  Now it's re-levelled on the spot it is.  It was hard doing as we didn't empty the tank fully but it's way better now and that corner is no longer lower.  However, after that occassion I'll be dreading this happening again regardless because the tank and stand are quite old and they won't hold the minimum of irregularity.
 Resealing the leaking seam is not permanent either because the old silicone is actually 1cm thick and the glass panels are not touching each other by design so I couldn't reseal it professionally without taking all glass panels apart which is not an option at the moment or actually ever. I'd rather buy another tank and stand and would have done so if I had the funds.
 I only sealed over the old silicone inside and out. That's the best I could do.  I used the CT1 sealant and it was pretty handy as it's non-toxic to fish and worked even under water as I splashed silicon all the way down just in case  The fish thought I was feeding them and were buzzing around my hands .  I was able to fill the tank above the leak literally a couple of hours after fixing it and it's been non-leaking since although I still have a large plastic container under the leaking side just in case  I am hoping there's no pressure going to the tank glass or seams anymore as that's the worst scenario.
So let's see how long it lasts.  I don't want to think about it leaking again and what I'd have to do if it does.


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## sciencefiction (8 Jan 2014)

Just to update that in the end I sealed a piece of glass over the side of the leaking seal and that has fixed the problem. Well, at least the tank the tank has been leak free for a few months but I've been afraid to fill it to the top since so now it's a bit like a riparium but keeps my mind at ease.


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