Cracks in my big tank!!!

[MacFanMr]

I'm actually out of town, but my roommate contacted me tonight to tell me that the 215g tank we've slaved over for months has developed several cracks in the glass all of a sudden. We have rock glued to the back glass over most of the aquarium, so we won't know until later if they exist elsewhere, but at the moment there are three large cracks and they appear to be isolated inside the overflow box. Shane is draining the tank and has transplanted all the plants to other tanks. Luckily there were no fish in the tank yet.

I may learn more after we disassemble it, but I'm wondering if you have any theories on why this failure may have occurred? I can think of three possibilities... (1) during manufacture, the glass didn't break cleanly and a chip or tiny crack was overlooked and covered up by the plastic trim, (2) the 500 watt (metal, submersible) heater that was located in the overflow box might have affected the glass on one of the couple occasions when the overflow box was without sufficient water and the heater was on, (3) my construction of the stand was faulty in some way and introduced stresses to the glass.

I would find it a bit hard to believe either of the last two options occurred as the glass is pretty significant and the construction seemed reasonably solid. The tank has had water in it for probably close to two months now on and off. Obviously it would be great if it was option one, but I don't know if there is any way to prove it short of removing the plastic trim which might destroy any evidence there is.

The tank is by Oceanic, I believe they have a warranty, but showing a defect might be challenging. I'm basically looking at starting over at this point, I would like to avoid having to buy a new tank again though if possible. If I did though, I might consider having it built with thicker glass and without trim or middle support. I would probably also revisit my design for the base, though I would hate to have to rebuilt the cubes and have to redo all the rock on them. I guess I would think twice about the rock on the back glass due to the (presumed) toxicity problems we encountered, but it looked nice so perhaps I would just make sure to have aquarium safe silicone this time and seal over any exposed liquid nails as much as possible.

I can't believe it... we were so close to completion... and while all is not lost, it'll probably be months until we can be going again. :-(

Michael

 

[ceg4048]

Sorry to hear about this disaster. I know it must be really disheartening. I've looked at the pictures on the link and I know it must be an obvious question but it doesn't seem like there was any gaps or foam relief under the base of the tank. The same question goes for the hood if any. Was it flexible or was room made for bowing/distortion of the glass?

Cheers,

 

[MacFanMr]

There is no hood... if you go to the front page of the blog and look through you can see most of the rest of the way it was setup. But you do have a valid question. How much does a tank need to flex? There is no foam, but it's not resting on a flat surface really either. I based it on viewing the standard fish store cabinets which only supported the edge of the tank, no support for the center. Really mine has support the length of the tank in the front and back and that's it. I mean there are beams going front to back but in such a short span I don't think they do much. They aren't glued or anything and are held there by wooden pins so it could flex front-to-back. But now that you mention it, the notching in the wood end-to-end was pretty tight I think. It wasn't necessarily intended to be, it just worked out that way. Still, the cracks began at the top of the tank... and unless we find more after moving the tank, are limited to inside the overflow box which seems an unusual place for them to form if it was a structural support issue. I would expect them to be closer to the center or right at the end. But I'm not a trained engineer, so it's possible I just don't understand how the forces are at work. I briefly tried to research how one can view stresses in glass... I know I've visited in the Corning museum of glass and with some polarization techniques you can view the internal stresses of a sheet of glass, but most of the stuff I found online was paid content and all I really have available to work with are some polarized sunglasses which may not do anything for me, but it was a thought.

Michael

 

[Tom Barr]

I something similar happen on a 120 gal, they forgot to silicon this small spot in the overflow. Wasted 4-5 days labor.

Regards,
Tom Barr

 

[MacFanMr]

I reviewed Oceanic's warranty and it says that it's covered for 5 years against leaks at glass-to-glass seals, and only if it was set on an Oceanic stand. So I'm pretty much out the money no matter how you look at it.

I will try to determine where a defect exists, if any... but it may be difficult to remove the trim without removing the associated silicone I'm trying to view.

Michael