Why Do Tanks Crack?

[twodoctors]

My AquaOne 620 is leaking, big time. There is a big crack that runs across the whole tank at the bottom (so big that one can feel the step when running one's finger along it). This tank was holding my mbunas. It had a layer of play sand (15-20mm) and a few pieces of tuffa rocks in it. Nothing's change for at least 6 months if not longer. Big leak out of the blue. Any good reason why it should crack?
 
Adrian

 

[Chad]

Sorry that happened to you! What a massive pain in the back side.
 
They crack for numerous reasons, which one it is in your case I can't say.

• Defective. This can a while to manifest and can be triggered by several things.
  Not made square.
• Imperfection in the glass.
• Micro cracks can be enlarged due to heater or just the weight of the water, rock, etc.

[*]Tank not level. Either because the floor or the stand.
[*]Rock causes chip or crack due to settling.
[*]Trying to move or shift the tank on the stand or the stand on the floor without emptying the tank first.
[*]Angry or vindictive person sabotages it.
[*]Earthquake.
Obviously we can come up with many more reasons but these are the common ones I've heard over the years with the most common being moving the tank.

 

[snazy]

That's horrible. I am really sorry.
 
I am not sure what it can be besides what tcamos already mentioned. If it was new when you bought it, then it's possible it has a defect on the glass or stand, or suffered a minor chip during transport that took time to develop.
 
You mentioned you had only 15-20mm of sand and rocks. Is it possible that the fish knocked some rocks without you noticing maybe?
 
It's really aweful. I'd be devastated if I were you. I hope you managed to solve the problem in a convenient way.

 

[twodoctors]

It's my mbunas that are suffering. All of them stuck in a 30L clearseal, 8 adults and at least 6 juveniles (lost count). The good news is they look fairly happy for the moment. New tank coming tomorrow with a bit of luck. Made a right mess in my room as well. Glad I wasn't renting and the floor wasn't carpeted.
 
I was just surprised. I bought it 2nd hand about 18 months ago. No problem until Tuesday. The tank even got me my tank of the month... not so luck after all. The rocks had been in place for a while. The crack runs across the whole tank. I'm guessing it was a small crack developing into a big crack. How I got the small one to start with I don't know. Certainly no signs of leak previously. No water change for about 9 days before (I was busy)...
 
Hmmm....
 
Adrian

 

[Lunar Jetman]

Sorry to hear about your tank.

I bought it 2nd hand about 18 months ago.

Unfortunately for all the care you have taken with it you will never be able to fully know how the previous owner(s) treated it.

 

[Sophie]

Not anything to do with the support underneath no?
Does it need/have polystyrene supports or a base made specifically for it?
Had a guy return one to the store the other day, had it running almost a year - Cracked and brought it back. Turns out he took the supporting base off it because he didn't like the look.
Might be just a newbie reason and you probably already know but just throwing it out there.

 

[twodoctors]

It's a AquaOne 620. It's all built in and I was using the original stand. 
 
I think it might be the rocks that I had. I had an accident changing the water about 2 weeks ago now where I took almost all the water out, and the fishes were flapping away on sand. Luckily I saw it in time and filled the tank up very quickly with no casualties. I think at this point the rocks might be too heavy for the base and develop a small crack. Over the next 2 weeks the crack got bigger and by Tuesday it's gone past tipping (cracking) point and it just gave way. My theory anyway.
 
It's all academic now. The Juwel Rekord 800 has arrived. Much better than the leaking tank. The mbunas are still trying to familiarise themselves with the new environment. They got so much more space it's almost rude not to add another species to spice things up a bit...
 
Adrian

 

[Shelster]

How frustrating....... But on the brighter side, it gave you the excuse to splash out on a larger tank have you posted pics somewhere of the new set up?

 

[bodge99]

Hello,
 
My 2p worth...
 
In my experience, problems such as these are often down to poor manufacturing and/or poor handling by owners.
 
Glass is a weird substance, people do tend to "take it for granted" that it is a rigid, strong substance... it is, but its particular characteristics (it is effectively a super cooled liquid.. i.e. no crystalline state at normal temperatures) means that it propagates cracks easily (glass cutting relies on this very characteristic!).
 
One potential problem with cut glass is how the glass sheet edges are prepared before the tank is assembled.
You will find that "better" tanks (i.e. **more** expensive) have the edges of the glass polished. This removes micro fractures that may exist from the glass cutting procedure.. These, coupled with any future edge impacts/stresses can cause failure... Yes, O.K. this is quite rare in reality, given the care levels normally given to a tank ... but it can and does happen.
 
If I'm rebuilding a (leaking) tank that is in otherwise excellent condition (i.e. has perfect condition glass with no scratches etc.) or is very large then I'll polish the edges before reassembly. This process is very easy to perform and only takes a little time... You have to be careful as cut glass can be sharper than a razor blade... A quality oilstone works wonders!
 
One last thing... Please don't dump the cracked tank... either repair it or pass it on to someone who will... This hobby is expensive enough as it is!
 
Bodge99

 

[Chad]

It's all academic now. The Juwel Rekord 800 has arrived. Much better than the leaking tank.

True, but if you can figure out how it happened for sure then it can be avoided for the future so still a worthwhile topic.

I am glad you were able to get a larger and better tank out of it though...that much is good right?