# Can I de-rim 29 gallon long?



## ilam (Apr 28, 2011)

I just want to remove the top rim on a 29 gallon long. 36x12x15h. I've read that the top rim doesn't actually do much supporting and that you can derim any tank without a center brace.. but I haven't heard of many people derimming tanks over 20 gal. CAN I DO IT?


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## Nicole (Nov 21, 2011)

How thick is the glass? 
Why take the chance?  Keep in mind that even if others have done it, doesn't mean it isn't prone to failure and 29gallons of water on the floor doesn't sound fun  
I don't think a small center brace in the middle would look too bad? Or a brace on each side if you want to keep the middle open?


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## ilam (Apr 28, 2011)

i went ahead and did it.. it's a lot of reasons hahaha, i cant afford an ada tank and i really like this tank size.

a lot of people have derimmed larger tanks and 29 gallon tanks. the regular 29 gallons are significantly taller which applies a lot more pressure to the glass than a shorter tank. if you use this tool, Calculate Aquarium Glass Thickness | Aquarium Tools.. i would only need to use 5 mm glass for a safety factor of 2.5 for a fully rimless tank. my tank has 6 mm glass and a bottom bracing which gives it a safety factor of over 4.

anyways.. those are my justifications, i just spent over an hour scraping silicon so im going to fill it up and test it now.


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## ilam (Apr 28, 2011)

here it is filled for testing, no noticeable bowing

edit: i just measured it, the middle of the tank is 1/8" thicker than the sides, which means each 36" panel is bowing 1/16". anyone know if this is within tolerances?


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## gklaw (May 31, 2010)

Ah it's a Hagen. The older the better. I de-rimmed my 105 Hagen - 5 ft long tank


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## jbyoung00008 (May 16, 2011)

You could always add a glass cross brace in the middle.


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## ilam (Apr 28, 2011)

my dad doesn't want it in the house without some support, so i think i'll buy a 4x12 piece with the same glass thickness and use it as a centre brace


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## mcrocker (May 29, 2010)

That amount of bowing doesn't sound like a big deal at all to me... I had a 33 gallon(rimmed) that bowed a lot, to the extent that I could see the larger gap in the middle with the naked eye. I never measured, but I'm sure it would be more than the 1/8th inch you have there. Glass is quite flexible.


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## Morainy (Apr 21, 2010)

I can't comment on the safety because I've never derimmed a tank, but it is attractive, that's for sure. I'm amazed that you could get the rim and silicone off in just an hour. You're way handier than I am!


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## ilam (Apr 28, 2011)

If anyone is interested, here it is with two 3x12 pieces attached










And here is one of the connections after a ton of silicon scrapping and cleaning to make it look nice


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## HIGHLANDER (Apr 9, 2012)

Good job on the new supports, if your tank had no center support on it to start with it'll be fine.
The plastic rim does almost nothing to support the middle of the glass, maybe some in the corners.


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## Scherb (Feb 10, 2011)

gklaw said:


> Ah it's a Hagen. The older the better. I de-rimmed my 105 Hagen - 5 ft long tank


Hello i agree. i have never derimmed a tank but Hagen is known for using thick glass and no center brace. Nice job bye the way looks good, and with the center braces you dad need not worry. nice you added the link. Cheers


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