Should I be worried about these seals?

[InfinityARch]

So a while ago I concluded a leak test of a 120 gallon tank I got secondhand, there weren't any leaks over the course of around 4 days. Because of preoccupation with work school/work (I'm a graduate student so they're kind of the same thing), I've kind of left the tank sitting dry for a while before actually getting all the plumbing assembled, and recently I noticed something odd looking about the seals, in the form of some silicone beads outside running along the bottom of the glass between the rim and the tank.


Can someone experienced with tank construction tell me whether what I'm seeing (in the pictures at least) is a potential problem, (ie an indication of an inner seam being extruded from water pressure and thus an indicator of an imminent seam failure) or something benign/normal?


Below is a picture that I took of the area of the seal that has me concerned.




And here is a picture from inside the tank looking up at the bottom of the tank

 

[skjl47]

Hello; I cannot actually tell from the pictures well enough to give a concrete answer but I will give an unsupported guess. Looks to me like someone ran a line of silicone over an existing seam. May or may not be a cause to worry and I may not be able to give a better opinion even if I were actually there.

I sort of have a rule of thumb on tanks bigger than 55 gallons. Having had a 55 gallon tank leak out on a wood floor over a basement that is about the biggest tank I will put on a floor where a leak can do damage. Even 55 gallons is plenty to cause damage.
I had a 125 let go in that same basement but no damage as it was on a slab with a floor drain.

Even if the tank were new there is a risk of a leak, so a used tank can have more risk. I have had new tanks leak and have had used tanks hold up just fine. I have had resealed tanks hold well.

That you are already concerned suggests that a better path is to test fill it again for a few weeks if you have a safe place to do so.

 

[InfinityARch]

Hello; I cannot actually tell from the pictures well enough to give a concrete answer but I will give an unsupported guess. Looks to me like someone ran a line of silicone over an existing seam. May or may not be a cause to worry and I may not be able to give a better opinion even if I were actually there.

I sort of have a rule of thumb on tanks bigger than 55 gallons. Having had a 55 gallon tank leak out on a wood floor over a basement that is about the biggest tank I will put on a floor where a leak can do damage. Even 55 gallons is plenty to cause damage.
I had a 125 let go in that same basement but no damage as it was on a slab with a floor drain.

Even if the tank were new there is a risk of a leak, so a used tank can have more risk. I have had new tanks leak and have had used tanks hold up just fine. I have had resealed tanks hold well.

That you are already concerned suggests that a better path is to test fill it again for a few weeks if you have a safe place to do so.

If the tank was resealed that's already cause for concern for me, since, if threads I've read on reefkeeping sites are to be believed, once you've got a large tank leaking resealing it basically sets up a ticking time bomb that will start leaking within a few years even the best case scenario, and the only way to properly reseal a tank is to completely disassemble it, remove all traces of siicone, and reassemble it from scratch.

And since that person was apparently a professional tank builder, I'm really inclined to believe them, and this basically means I need a brand new tank if you're right about it being resealed.


Edit: I also asked about this on reddit, and one person said it looked to them like leftover silicone from when the frame was being put on that was squeezed out; just to be clear if there's confusion about this, those beads of silicone in the first picture are not on the inside of the tank, they're on the exterior.

 

[skjl47]

If the tank was resealed that's already cause for concern for me, since, if threads I've read on reefkeeping sites are to be believed, once you've got a large tank leaking resealing it basically sets up a ticking time bomb that will start leaking within a few years even the best case scenario, and the only way to properly reseal a tank is to completely disassemble it, remove all traces of siicone, and reassemble it from scratch.

And since that person was apparently a professional tank builder, I'm really inclined to believe them, and this basically means I need a brand new tank if you're right about it being resealed.


Edit: I also asked about this on reddit, and one person said it looked to them like leftover silicone from when the frame was being put on that was squeezed out; just to be clear if there's confusion about this, those beads of silicone in the first picture are not on the inside of the tank, they're on the exterior.

Hello; First I am not there and my guess is just that, a big guess. For example I did not understand that the first picture was of the outside of the tank. Do not take my previous comments as being properly informed. For what it is worth the seams pictured look fine in the pictures. I only had the impression there may have been a new line of silicone because the pictured area is a tiny bit sloppy. May be a factory seam for all I know.

My take is that there may be essentially two seams of silicone used when a tank is assembled. The more important being when the glass panels are actually first put together. After that there may be a second line of silicone laid down on the inside corners of the tank. That second interior line may be more a form of insurance against leaks. I also have learned from doing my own reseals that a not so pretty seam that is laid down well is good enough. I have tried to pretty up a line of silicone only to make a mess. Any more if I get a decent seam put down I leave it alone even if it does not look great.

I have resealed many tanks without taking them apart and most have held up just fine.

As I posted before, may be the only way to ease your mind is to test fill the tank for a time long enough to give confidence. Only you can know how long that may be. Usually if a repaired tank is to leak it does so petty quick, often right away. The tanks that failed for me had been in use for months at least and the 125 for a few years.

good luck