Post Mortem

[sNEIRBO]

Now that I've settled with JBJ, here's my post mortem / engineering theory for the cracks.

 

Saturday when my tank cracked, Detroit had a 95 degree day going. One of those lovely Michigan hot / humid / sticky / crappy days. I was out of town Friday night, and I turned the A/C off before I left the house. Normally the house stays around 77 degrees until about 4:30 then it jumps up really high - I lose my tree shade around that time and the attic heats up. Usually by that time, I'm home and I either open the windows or crank up the A/C to cool the house off. Again, I was out of town on Friday. The house got hot - probably went up to around 85 or warmer in the house by Friday night, and never cooled down. Saturday was another nasty day, so it either stayed hot, or got hotter in the house during the day Saturday. The thermometer in the house read 87 when I walked in to see the mess Saturday afternoon. I had left a fan running on the tank to keep it cool, but it was blowing on the opposite side of the tank from the crack.

 

That's the setup - here's my theory -

 

The fan was blowing on the left side of the tank keeping that whole side and the front and back of the tank cool. The other side was probably not getting any cooling from the fan. The temperature differential between the front and the right side was probably pretty extreme. Thermal expansion was playing tug o' war with the tank. Left side was coolest, right side was hottest, front and back were in between. Engineering 101 tells us that failure only happens in tension. Tug o' war! If there was an imperfection in the glass, a bad design in the corner of the tank, etc., something had to give - CRACK!

 

Keep in mind, most "normal" tanks are made from straight pieces of glass that are caulked together. The caulk is a buffer, it stretches, it shrinks, its a lot more pliable than glass. Most "bowed" tanks are made out of Acrylic - again a substance that is a lot more pliable than glass. A material that will move, shrink, expand. Glass doesn't like to move, shrink, or expand.

 

Here's a question for all of the other cracks that have been reported on this site the past few days -

 

Were there similar conditions when your tank "popped"?

 

Was your tank located near a furnace register that might have been blowing on one side of the tank?

 

Did you have a fan situated as I did, only blowing on one side?

 

Was the temperature inside your house considerably warmer than the water temp in the tank?

 

If this is the case, I'd say that everyone who owns a Nano Cube needs to look at their ventilation systems in their homes. Make sure nothing is blowing on only one side of your tank. If you need a fan to keep your tank cool, use two, one on each side. If you have a HVAC register that blows directly on your tank, add a baffle or deflector to redirect the flow.

 

Just some thoughts and some questions. Maybe if we put all the data together on the fialures we know of, we can come up with a solution to the problem.

 

As for me, my Cube is now located in a more thermally consistent location of my house - my basement! And I'm off to PetSmart to see if I can find some carpet cleaner to get this God awful stink out of my Office carpet!

 

Cheers -

sNEIRBO

[Web Guy]

I do not think my temps in my house fluctuate enough on one side that running a fan on the other side matters. House temps are always around 78-77 and tank runs at 80.6. Maybe if direct sun light or something was hitting one side of the tank.

 

But I could see your case in RARE cases.

[artarmon42]

Without offending anyone, aiming a fan at one side of a glass tank is pretty illogical to me...

 

It either doesn't work (because the glass is sufficiently insulating) and nothing happens.

 

Or it works, which will clearly indicate that the one solid piece of glass has a large temperature differential (one side is stable/rising, the other side is not only cool but is cool enough to reduce the tank temps).

 

Now we know it works, so it must be the later stressful scenario.

 

To be clear, I'm not saying the fan caused the crack. I'm just saying that if the glass is imperfect or insufficient for the stresses, then blowing cool air against the glass is just one more straw on the camel's back... Other stresses would include stacking rocks against the glass and knocking on the glass: why tempt fate unnecessarily.

 

If you want to use a fan, use it to blow ACROSS the water surface. That's evaporative cooling at it's optimum.

[sNEIRBO]

I wasn't using the fans to cool water, I was using the fan to cool a hot room, the fan happened to be in the doorway blowing across the cube. There's nothing in my tank that should be raising water temps - stock lights. I'd only noticed water temp increase due to ambient temp increases. So I was trying to keep the room as cool as possible. It just happens that the Cube was in the path of the fan blowing air into the room. At the time I didn't know there could potentially be a problem with thermal expansion stress cracks in the Cubes. As a post mortem analysis the possibilty of contributory thermal stress due to the fan occurred to me.

[steelhealr]

Hi ...I'm not an engineer, but, I doubt the fan had much to play here. Water is obviously more dense than air and it takes a lot of energy to raise water temperature. I think that simply the rising temp of the house against the glass would have been enough to stress weakend glass. For those more knowledgable than I, if sNEIRBO's tank temp was in the late 70's and the house temp rose to the high 80s, is a 10 degree differential across the glass enough to cause a stress crack?? SH

[rbonin]

The conditions that sNEIRBO describes were not in effect when my 12G NC cracked at one month. In my case, I think the causes (other than imperfections in the tank itself) were (1) an imperfect level and (2)having one large rock touching the side glass where the crack occurred.

 

-Rick-

[Web Guy]

I am keeping my extra 10 gallon around in case it every happens.

[necat2]

Dear sNEIRBO,

 

It was partly due to your post that we acted so fast with our Nano crack situation

http://www.nano-reef.com/forums/showthread...&threadid=60207

 

There is a product on QVC many swear by to eliminate odor. Here’s the link

http://www.qvc.com/asp/frameset.asp?class=...HOMEIMPROVEMENT

 

If you’re not happy with the results you can get a full refund within thirty days. Hopes this helps.

 

P.S. I don't think these will show up as a true link, so the product's name is Don Aslett's X-O Plus+ Odor Neutralizer and Cleaner

 

Nadine

[gedemeister81dk]

hi

 

great teory, but IMO not the case, the temp difference has to be alot higher to crack glass, the prob. is badly made glass (it´s brittel stuff and is not alwas perfect) or it´s been put under some kid of force (twisting ect. ect. )

 

gede

[steelhealr]

Sorry...another cracked cube. SNEIRBO...PM ME. See my new post. SH

[sNEIRBO]

SH -

 

Your mailbox is full, the PM won't go through. I'm running down to my basement now to check the new cube.

 

sNEIRBO

[steelhealr]

I'll empty it...this is a problem...DEFINITELY. This is not shipping damage. Although other tanks are doing well, I wonder how many will develop stress fractures. You know...I really did feel very badly for you when I read your post, hence, my following it along. As always in life, it's a lot different when it happens to you. I'll quote you..this sucks. SH

[pastelball]

I had a JBJ Nano Cube it cracked after about 1 month. Good thing I had a empty tank handy. It cracked like at 11:00pm not many LFS open. I think that it is cheap glass.

[sNEIRBO]

SH -

 

I'm the first person in line for you sympathy party. A week ago I was in the same boat, and by the looks of it (check your thread for my lastest post) I'm not out of the woods yet!

 

PM me, let me know what I can do to help.

 

Does anyone else think a real website might help bring attention to this problem? I'm willing to start up "nanocubessuck.com"! Especially if Cube-2 goes POP!

[steelhealr]

sNEIRBO.....nothing to do for us right now except support and see how JBJ responds. I believe most people are fair, so, their response I think is key. If I had a large company that was selling a large amount of product, I don't think replacing a handful (or more) would be such a great loss. HOWEVER, I'm not sure having them ship me a freebee is really what I want either (who'd sleep well not knowing if it's going to crack again?). Certainly it would better than having a cracked one and also save anyone the expense of having to invest in a new system. Would it crack again?

 

The real question is whether or not they are simply going to push product on the public or now make a move to say..."HEY..we're having problems with this over here and we need to rectify it right away." I think that you can see how concerned I am in view of the complete 'about face' I have made with regards to my thread. SH

[sNEIRBO]

SH -

 

The irony of this is, when I was looking for a Nano Reef I did a LOT of research. I had several tanks picked out. First on my list was a 60 Gallon Acrylic, but the thought having to pick out the pumps, filtration, etc. kind of had me spooked. I liked the Nano Cubes, but I was being steered away from it by one of the bigger Fish Stores in Detroit, because of the small size of the tank. Do you know what changed my mind about the Nano Cube - your original Newbie Set Up thread. I must have read that thing a dozen times and I finally said "This guy is excited about this system" and he makes it sound fun, easy and enjoyable.

 

You've seen most of my posts, I had a rough time getting this Cube going, but I was enjoying the hell out of the mods I was doing and I was anxiously awaiting my tank's first inhabitants. I think I was as enthusiastic about this product as you were. And now look at us. We're both sleep deprived skeptics. (I got up twice last night to check to make sure the water was still in the tank!)

 

I'm with you, I want JBJ to replace my tank so I have SOME piece of mind, but I don't trust this tank any further than I can throw it at this point. I will be much happier when Chris gets the Acryli-Cube in production and I have one sitting atop my Nano Cube stand!

[Chronicles]

FWIW I have a tower fan that shoots at the left side of my cube every single day, this is between the AC vent and my cube, so the air temps change constantly through the day.

[steelhealr]

....so SNEIRBO...how do you think I FEEL..starting the thread and then having a crack in the end??????????? I'll take the blame for starting you out on this path and I'm going to blame Aquarium Adventurs for having a really cool 12 NC and the sales rep telling me that the 24 was better because it had more volume. I think I may just take some pix and go back to my thread later to get my mind off this mess. SH

[Chronicles]

fack... steelhealr go check your thread...I found something :*(

[steelhealr]

Saw it...Chronicles..get your finger in there and feel if there is a stepoff. If you have one, ballgame over for NC. SH