Jestersix

500 gallon CAD Lights disaster

Terrible customer service. Feel sorry for the guy.

Hah. I have a brand new cadlights tank sitting in my living room. Guess I should've sold it last month.
 
man wonder how that happened, looks like the bottom burst out which threw the front of the stand across the room, then couldn't hold up under the weight and fell to the ground.
 
Wow.... that's all I can say. Yes that IS EVERY reefers nightmare.

Hopefully insurance covers all of that ( HOUSE issues ).... wonder if the wife will let him keep a tank again?
 
Looking at those pictures, it seems there might be a big design mistake on the tank.
Hard to tell for sure, but it appears the front face was face-glued to the bottom and sides.
You really want to glue the front to the top of the base.
Meaning, you set the base flat, put glue on the top of that, then set the face down on top of that.
From the pictures, it seems like it was glued horizontally, so glue is on the edge of the base.

Issues if it was done that way:
1) Glue joint is purely in tension, not shear. Weaker.
2) Bottom is usually thinner, which means in this case, glue joint is thinner, by a big percentage if 3/4- > 1/2
3) As tank flexes that joint is now in what you call "peel" mode. Meaning higher load on one side than the other.

An expert on that specific glue used would have to speak up, but a guess is that those issues cut the strength a LOT.
Perhaps in half, perhaps more.
 
Nope, you actually want the bottom piece inside the front back and side as it looks like it was done. It could have been a number of issues. Playing devils advocate, how do we know it was totally CAD lights fault? The house was recently renovated, which means the tank was probably moved at some point. How do we know something did not happen to the tank when it was moved. The only thing the OP stated was that the failure was "deemed as a result of the manufacturing process." Why does he not state specifically what caused it?
 
iani said:
Nope, you actually want the bottom piece inside the front back and side as it looks like it was done. ....
Click to expand...

I am really surprised to hear that. Would love to hear the theory on why.
I am an engineer, not a tank designer, but to me, it does not make sense from an engineering standpoint.
Larger joint is better than smaller joint.
The way glass/glue bonds is mechanical, so usually much better in shear than tension.
Especially for dead-loads.
And you get the peeling effect as front bows out, if bottom is inside. Could double the force.
But I certainly could be missing something.
 
Well for your standard glass tank I would assume it's due to the trim around the bottom of the tank, while yes it's plastic that's still something else holding back the glass, and having more surface contact adds more strength, but for a trimless tank that's obviously not true, I would think perhaps because you don't want the weight of the glass to squeeze out any silicone, while yeah you could use spacers but perhaps you don't want spacers there? I dunno just guessing.
 
quoted from someplace on RC
The shear, and tensile strength, of the silicone is irrelevant in this case, as neither has anything to do with holding the tank together. Those properties deal only with the silicone itself, e.g. tensile referring to what it takes to pull the silicone apart. The shear strength refers to what is required to shear the silicone apart. The weakest part of the chain is the weakest link. In the case of bonding glass for an aquarium, the property we are concerned with is the adhesive strength, or "peel" strength. This is the WEAKEST property of silicone, and therefore is the only one we are concerned with. Other properties are irrelevant.

Seems like it would be easiest to peel apart when silicone is loaded in a shearing fashion. I am not sure.
 
I tend to agree that the weak point is the silicone-glass bond.
But I was talking about sheer/tension on that bond itself. Not sheer pulling silicone apart.

Speculation is this:
Microscopically, the silicone is stuck to all the tiny bumps and ridges of the glass.
With force aligned with surface (what I was calling sheer), it seems like that bond would be better.
Think sliding sandpaper versus pulling it off.
But maybe not.
While silicon itself may not break, it is the first to deform, and that may affect it more.

As far as peel, I was thinking more like tape, where you have an imbalance of force.

I looked pretty hard, and I do not see anyone having tested it.
Which is weird. Seems rather important, and really easy to test.
But all my tanks are acrylic....
 
No I get where you're coming from, just don't know what the sheer stress on silicone are, nor it's adhesion strength specifically to glass.

All I know is when I fixed up a Leemar tank that was broken on the bottom pane it was a PITA trying to get it out because it was inside the sides.. eventually I had all I could and decided to hit it with a hammer really hard, that was actually worked fairly effectively. Ended up making a PVC bottom with a L groove so I had the best of both worlds both inside the sides and ontop of the bottom :D
 
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