is my 75 gal going to break?

[PikachuSalad]

I bought a used oceanic 75 gallon glass aquarium. When I filled it with water to test for leaks, I noticed some distortion - the line of the bottom edge in back seems to pinch inward (bending toward the front of the tank) at the edges - the kind of distortion I used to see with my old 55 gallon acrylic tank (only not as bad).

I was under the impression that I wasn't supposed to get such a thing with a glass aquarium?

It does have a center support...that appears to be intact.

Is this thing getting ready to explode, or is this "normal"?

 

[Anonymous]

Wow, I have never seen anything like you describe on a glass tank before, but the center brace being intact is an interesting detail.

 

[Len]

So it's bent inward and not outward? That is very odd to me too. If the tank stresses, it usually "bows" outward. I'm honestly not sure what's happening with your tank. It may have simply been assembled that way (perhaps the center brace is pulling the middle section of the front and back glass together towards the middle), although I'm not sure why the manufacturer would do that either.

 

[PikachuSalad]

Sorry...I'm not very good at explaining...I'm pretty sure it's bowed outward, which is causing distortion when looking through the water from the front. I will snap a pic later today when I put water in it again (after work), but for now, here's a diagram of a top view to show what I'm seeing when I'm looking from the front (if I haven't made this confusing enough)....

So, the black is the actual glass of the tank. The red is the distortion I'm seeing (not the actual shape of the tank).

This is the same type of distiortion I saw on my old acrylic tank - the reason I got rid of it and decided to get a glass tank.

 

[Anonymous]

Glass tank bows too, just not as much as acrylic. The distortion you see is consistant with it due to the bowing near the center of the front panel.

 

[Reggie]

There are a number of ways to check to see if this nothing more than an otical illusion or if in fact the tank is bowing.

1. Make a simple plumb-bob with a piece of string and a small weight on it and dangle from the top of each corner - while the tank is empty. Assuming your tank is completely level then the line would stay against the 4 corners from top to bottom.

2. Measure the tand at the top from front to back at the left, middle and right of the tank.

3. Measure the bottom of the tank at the left and right - doubt there is a way to measure the center so forget about it.

Fill the tank and repeat steps 1 - 3

Compare top measurements to bottom as well as the plumb-bob (verticality). If your readings and measurements do not change (measureably) then what you have is an old fashioned optical illusion. There must be a logical and physical distortion in the measurements or verticallity of your tank otherwise leading creedance to the optical illusion.

If your measurements reveal the sides are shorter than the middle your brace was mis-measured and is too long.

There are some additional checks for squarness but that is normally a 2 person job and requires a much more detailed explaination. I believe you will come to a conclusion utilizing this.

Good luck.

 

[Anonymous]

I thought that glass wouldn't bend far enough to be noticed when it has not been heated. Glass is extremely brittle at low temperatures and doesn't have much(extremely low) plastic distortion. Glasshas virtually no deformation before it fails. It will just fail. This was my take upon glass.
Acrylic tanks are different, can bow as the material is more plastic than glass.

 

[Reggie]

Your 100% correct the yeild (plastic distortion) in glass is virtually 0. Actually it was a feeble attempt to prove it is most likely an optical illusion. The more physical facts a person has allows them to rule out other possible factors and theories. As you say since glass allows essentaillly for no distortion then it cannot bend lending creedance to the fact when full it is an illusion.

This is the way I see it anyway.

 

[Anonymous]

I went found a case were a tank glass did distort, it was on a sheet of glass 8 ft in height and 12ft in length.
An easy way for him to see would to just run a spirit level along the front.