Bulging Tank

[Surprise_Clown_Loach]

Question on the condition of my tank.

I purchase the tank used, and PO stated he had it for some ~ 6-8 years.

I noticed recently, that the tank hood has about ~ 1/8" gap between where the glass and hood meet. (in the middle most part of the longest span of the tank) The tank is bulging.

Is this normal? Should I be concerned? Guess I can take a pic.

Tank dimensions: 30"x12.5"x18"

[Orion]

You say there is a gap where the hood and the glass meet, so is there no top frame on the tank? If not then this is why it's bowing a little.

I've got a 40 gallon breeder that's old and doesn't have the center brace and it bows close to .5 of an inch when filled with water. The newer tanks have a lot going for them in terms of structural stability, but that's not to say that old tanks don't have some love left in them.

[Surprise_Clown_Loach]

There is a frame, just no center brace. I took a tape measure to it, and it's .5" wider in the center. The pics didn't come out well, I'm not very good with the camera.

Thanks for you quick response.. :O

[Orion]

I don't know if your in any trouble or not, but for only a 29ish gallon tank, that's a lot of bowing. I've never seen any tanks under 3 foot that have a center brace.

Best thing I can say is keep a close eye on it, and inspect all the seems as well as the frame for any peeling or cracking. There are some DIY ways of making a center brace if you want to look into that too.

If it were me I might just think about a replacement tank, but as a worst case scenario. But I'll be first to admit I'm a bit paranoid when it comes to tank safety and stuff like this.

[brian1973]

Originally Posted by Orion

If it were me I might just think about a replacement tank, but as a worst case scenario. But I'll be first to admit I'm a bit paranoid when it comes to tank safety and stuff like this.

I had 29g about 15yrs ago that broke right after I filled it, I went out to get filter, etc for it and came home to my dresser and floor full of water. I would replace it.

[Kalavek]

I used to volunteer at the lagoon in West Edmonton Mall. Under the surface of the lagoon are (or were) several room-sized tanks that were viewable from the submarine attraction. A thick partition of glass or polycarbonate sits between the lagoon and the tank, so the tanks could be completely drained for maintenance. When you drain one of those tanks and climb down inside (depth of something like ten feet) you could see the partition bowing several inches towards you.

Also, just looked at my 25 gal - I've got the same thing, the center of the tank bows out, same amount as yours does. Here's to putting faith in that top frame.

So, is this a genuine concern, or is this fairly normal for this size tank? The glass on mine is 3/16".

[brian1973]

Originally Posted by Kalavek

I used to volunteer at the lagoon in West Edmonton Mall. Under the surface of the lagoon are (or were) several room-sized tanks that were viewable from the submarine attraction. A thick partition of glass or polycarbonate sits between the lagoon and the tank, so the tanks could be completely drained for maintenance. When you drain one of those tanks and climb down inside (depth of something like ten feet) you could see the partition bowing several inches towards you.

Also, just looked at my 25 gal - I've got the same thing, the center of the tank bows out, same amount as yours does. Here's to putting faith in that top frame.

So, is this a genuine concern, or is this fairly normal for this size tank? The glass on mine is 3/16".

I have a 29g and a 25g that are atleast 8yrs old and neither of them are bowing like that.

[Orion]

There's a huge difference between a few thousand gallons, and 29 gallons as well.

It might not be an immediate concern, as in the tank is gonna crash in the next hour, however it is something to be concerned about. A tank this small should not be bowing out that much. Less than 1/8" at most would be close to normal I would think, with the tank full of water, and the measurement taken dead center at the top. But ideally none is best.

[Kalavek]

Originally Posted by brian1973

I have a 29g and a 25g that are atleast 8yrs old and neither of them are bowing like that.

Great, now I'm getting paranoid too.

Structurally speaking the frames should, if sealed properly, prevent the sides separating from the front and back. (Right?)

I know glass will flex quite a bit before it breaks - I recently had a 24" x 24" x 3/4" piece of tempered glass deflect a bit more than an eighth of an inch when it was used as a window on a vacuum chamber. But then again, my tank doesn't have 3/4" glass. And I have no idea how old it is.

[brian1973]

Originally Posted by Kalavek

Great, now I'm getting paranoid too.

Structurally speaking the frames should, if sealed properly, prevent the sides separating from the front and back. (Right?)

I know glass will flex quite a bit before it breaks - I recently had a 24" x 24" x 3/4" piece of tempered glass deflect a bit more than an eighth of an inch when it was used as a window on a vacuum chamber. But then again, my tank doesn't have 3/4" glass. And I have no idea how old it is.

I think you mean 1/4" glass thickness .. I know I have those tanks in my garage for atleast 7yrs before I set them up and I bought them used from a pet store that was going out of business. I will measure them tomorrow or later tonight but wondering if you dont have terrarium tanks instead of aquariums, they use thinner glass on terrariums because they are not meant to hold water.