# Tank flex/bulge?



## rtfish (Oct 2, 2014)

As I was filling my tank with lovely rrf and water lettuce from a great raok on these forums, I leaned in on the front of my 40g breeder with my hand and to my shock the glass "moved". Noticed this by the movement of the water in my tank. Checked and the glass moves enough when I put pressure on the front of the tank that I can see the difference in the black top brace when I exert a small force and then release. Is this normal to get a bit of flex on the tank in the middle of the long length sides? Perhaps it is more accurate to say is it normal to get a bit of bulging in the middle of your tank? This is the first time I noticed, and it is my first larger tank so have not encountered this before. Some searches on the googly appear to say some flex is normal. Please tell me this is true!


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## pantherspawn (Dec 21, 2011)

It can be normal, or it can be a problem with the brace. Depends on the specific tank and the base it sits on. 

Sent from my SM-N910T using Tapatalk


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## oldpunk78 (Nov 1, 2008)

It's normal. I had a 29g that probably had a about 3/16" bow in the front.


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## rtfish (Oct 2, 2014)

AGA 40g breeder 38x18. The model without the center brace. On the AGA black pine stand they make for it. Checked the back and it has a bow as well, but the top brace is much more fitted in the back. This is probably why the versa top when I pull it forward hits the middle edge of the brace on the front.


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## PlantedRich (Jul 21, 2010)

Normal! We often worry about glass bending and breaking but it does flex. Not the best thing but it happens all the time. When stores had large glass display windows, you could see them flex as strong winds hit them. Building canopies showed me that I had to allow some room for flex when fitting them down over the top. 
One big learning experience was building a top which had a lid fit down over the front. When empty it worked great but when the tank was filled the lid was jammed so that it had to be trimmed to open right.


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## Kubla (Jan 5, 2014)

It's normal but I certainly wouldn't recommend leaning on it at all or trying to make it flex unless you're trying to find the breaking point. Water applies a lot of pressure but it's a very even pressure.


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## Bushkill (Feb 15, 2012)

Agreed that it's "normal". 

I don't particularly care for the sight either, but it doesn't matter who makes them. The adhesives, one-piece and braced trim make blowouts really hard to achieve. The ones that fail, usually have some workmanship issues, or they've been mistreated at some point.

I have a few 29G's that bow a good 3/16" as well. Being in a breeding settup, they are lined up to be viewed through the end panel. Stoopid me cut glass tops based on the distance between the corners with a little expansion room. When I laid the back half on top of the tank for the first time....well...I can't type the words that came out of my mouth when the other end of the end of the panel fell right in to the tank when I let it go. The real problem was Tetra tanks make it worse by having much smaller lips on the inside of the top trim.

Don't sweat the bowing. The key is the silicone between the five panels of glass.


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## rtfish (Oct 2, 2014)

Sent AGA> Aqueon> Central Aquatics a query. Response:

_Thanks for the email!

Bowing is a normal part of aquarium design. The longer or deeper the panel the more the aquarium is expected to bow. Glass has a degree of flexibility that allows it to bow without any risk of cracking or breaking. The Central Aquatics standard for normal bowing is ½ of the thickness of the glass wall. The standard is based on what we feel is what a “normal” amount of bowing should be. Other brands use different standards or no standards at all. It is not uncommon to find high end rimless aquariums that bow more than double the thickness of the glass._


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## Immortal1 (Feb 18, 2015)

rtfish said:


> Sent AGA> Aqueon> Central Aquatics a query. Response:
> 
> _Thanks for the email!
> 
> Bowing is a normal part of aquarium design. The longer or deeper the panel the more the aquarium is expected to bow. Glass has a degree of flexibility that allows it to bow without any risk of cracking or breaking. The Central Aquatics standard for normal bowing is ½ of the thickness of the glass wall. The standard is based on what we feel is what a “normal” amount of bowing should be. Other brands use different standards or no standards at all. It is not uncommon to find high end rimless aquariums that bow more than double the thickness of the glass._


Thank you for posting this. I built a custom 40 gallon rimless. Very careful measurements showed the 1/4" glass panels bowed a full 1/16" each when full. I can now sleep better


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## MrJack (9 mo ago)

I'm having the same problem now with my 40gal. It's 36 inch long. The center bowed out 7/8 bigger than the corners measured. There's no center support on mine. And the floor and stand are completely level. I drained mine. The seals on the corners have a ton of bubbles now. There's no way I'm filling that back up. I'm taking it back and getting something with center supports


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## somewhatshocked (Aug 8, 2011)

MrJack said:


> I'm taking it back and getting something with center supports


With that much bowing along with bubbles in the silicone, that's a good idea. That aside, just doing it for peace of mind alone is probably worth it.


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## MrJack (9 mo ago)

Yea, it's going back. And I found a 60gal breeder kit with everything I need. So, ima just get that. Kind of a blessing in disguise. Haha


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