What makes aquariums fail and burst?

[Schuyler]

Many episodes of AFV and almost ever intro to Fish Tank Review has a video of a fish tank just completely shattering or bursting.

On the other hand there are videos looked that one where the guy puts like 200lbs of rock in an aquarium and jumps on it to show how strong tempered glass can be.

What causes those total failures and what are some things that can be done to prevent them?

[The endler guy]

Now I have absolutely no experience with this but it probably is the silicone bonding being weak (even though silicone is used to hold cockpits of supersonic jets)

[EVoyager31]

Well I'm sure it would be a mixture of things.. though I have only ever had leaks (and what would likely lead to a burst) when the tank was not level. When it is unlevel it puts too much pressure on one side and it starts a slow leak.

[TOtrees]

For argument's sake, let's confine the conversation to glass tanks. Sure we can bring acrylic or others into the mix, but if you want to do so just make it clear (LOL see what I did there?).

I'm writing this off the cuff, and I'm not an engineer. If you see a flaw in my logic/meanderings, pls chime in. 

There are 2 main types of (glass) aquarium failures: bursts and leaks. I would classify cracked glass as a burst (even if it's a slow leak). 

Leaks occur when the glass walls (or floor) remain intact, but the seams let water through. Could be due to age and degradation, could be due to physical damage (to the silicone), could be due to pressure forcing the panels/seams apart. Correct me if I'm wrong, but if your tank is leaking and all 5 panels (4 sides plus bottom) are intact, it's got to be the seams/silicone. 

Bursts and cracks occur when glass is subjected to forces that exceed its strength. Strength will vary depending on the direction of force, relative to the piece of glass. You'd have to squeeze a piece of glass really hard, using a very sharp and hard object, to crack or break it. But if you bend, twist or torque a long piece of glass (esp if it's under pressure), it will break under much less force. This is why rimless tanks need to be on a very flat surface. A single piece of gravel under the corner of a full (rimless) tank can break it. Rimmed tanks solve this problem by suspending the tank in a bed or wrap of slightly flexible silicone and plastic, so the weight is transferred evenly all the way around the outside of the tank, to the plastic rim. It should still be generally flat, but it will tolerate a bit of twisting of the plastic frame (eg due to a not perfectly flat stand) because the frame and silicone protect the glass inside it from twisting. 

Understand the difference between flat and level. Level refers to being even with (or parallel to) the horizon, eg 0 degrees of inclination or slope. To check for levelness, you need a level. Flat simply means flat across a single plane. A surface (like a stand) can be flat and level, flat but out of level, or not flat and not level. What about being level, but not flat, you ask? Well, technically if a surface is not flat (ie it has some kind of twist or warp), then different parts of the surface will have different angles or levels. It might be level on one side, but not at another corner. So a non-flat surface cannot be said to be level. At least not for this discussion. 

How to prevent breaks? 

- Buy used tanks with caution. How old is it? What's the condition of the silicone? Has it been modified in any way? Signs of being poorly cared for? 

- Inspect new tanks for defects before you fill them. It's easy to return/exchange a new/empty tank, less so once it's filled with water and critters. [defects could be chips/cracks, missing silicone, edges that don't line up the way they should, etc]. 

- Make sure tanks are on a flat surface. They don't have to be level, but it should be flat. 

- Make sure the weight of the tank is transferred evenly and correctly to a strong and even floor. Use adjustable feet/legs or shims if necessary. Stands shouldn't wiggle or wobble. If you bounce up and down on the floor and water starts sloshing, think about making changes. This is less critical for smaller tanks, but once you get upwards of 20 gals, a little sloshing can move a lot of water weight around. 

- If you see algae or dirt between the silicone and glass, you need to replace or reseal the tank.

[JettsPapa]

On 12/20/2022 at 10:15 AM, EVoyager31 said:

Well I'm sure it would be a mixture of things.. though I have only ever had leaks (and what would likely lead to a burst) when the tank was not level. When it is unlevel it puts too much pressure on one side and it starts a slow leak.

I would like to clarify something.  Placing a tank on a surface that isn't level doesn't cause them to break (at least not the moderate amount of lean likely to be found in a house).  If it did most of mine would be leaking.

Placing the tank on a surface that isn't flat can cause a tank to break.

[Winstons_estate]

On 12/20/2022 at 11:11 AM, Aiden Carter said:

Now I have absolutely no experience with this but it probably is the silicone bonding being weak (even though silicone is used to hold cockpits of supersonic jets)

Just clicking on this subject made me sick to my stomach 😛 This comment made me feel a lot better though

[Patrick_G]

On 12/20/2022 at 10:39 AM, JettsPapa said:

I would like to clarify something.  Placing a tank on a surface that isn't level doesn't cause them to break (at least not the moderate amount of lean likely to be found in a house).  If it did most of mine would be leaking.

Placing the tank on a surface that isn't flat can cause a tank to break.

True! 

[Flumpweesel]

Glass can become brittle with age so don't trust that tank that someone found at the back of garage at house clearance. 

Keep an eye on chips and deep scratches these can become issues (just like with a windscreen) if they get put under stress.

Try not not to move tanks every move puts a tank under various forces as it's maneuvered especially rimless aside from the risk of something going wrong each time.

[Biotope Biologist]

I’ve only ever had a failure due to old/damaged silicone. Also don’t buy reptile tanks and expect them to hold water. The glass is thinner and over time they will burst. Other than that I wouldn’t be concerned.

 

I bought a 55 long in college for $20 because it leaked. i put water in it for 2 weeks with a powerhead with 0 leaks. Shrugged and put it in my living room for 3 years before I sold it.

 

Alot of it is fear mongering, maybe because it’s impossible to make tanks for cheaper than the $1 per gallon sale. So what better way to sell your tank for 3x that than to tell someone cheap tanks aren’t strong enough to hold water long term like theirs is.

[Schuyler]

On 12/20/2022 at 6:50 PM, Biotope Biologist said:

The glass is thinner and over time they will burst. Other than that I wouldn’t be concerned.

You know... I bet that's what most of them are.