DIY 8x2.5x2.5 ft tank question

[batang_mcdo]

Hi,


I'm planning to build a 8x2.5 x.2.5 ft tank. got the dimension needed for building a 8x2.5x2.5 ft tank from http://www.garf.org/tank/BuildTank.asp.


But i have a question. I noticed that the buttom glass? in only 95 " x 29"? shouldn't it be 96 x 30 also?




Tank Information:

Material = Glass
Tank Height = 30"
Tank Width = 30"
Tank Length = 96 "
Glass Thickness = 1/2"
Approximate Gallons = 374

​

Cut List:

Bottom = 95 " x 29"
Front = 96 " x 30"
Back = 96 " x 30"
2 Sides = 30 " x 29"
Top Front/Back brace = 95 " x 2"
Top Sides brace = 29 " x 2"

​

 

[Pharaoh]

You have to account for the thickness of the panes of glass. When you build this, the side panes will be next to the bottom pane, which should give you the 30".

 

[nomad]

.......I would go with 3' width

 

[nolapete]

But i have a question. I noticed that the buttom glass? in only 96" x 29"? shouldn't it be 96 x 30 also?

They are idiots and have it where the front, back, and sides don't rest on the bottom glass. Dumb, dumb, dumb. The sides, front and back, should all rest on the bottom glass.

Bottom = 95 " x 29"
Front = 96 " x 30"
Back = 96 " x 30"
2 Sides = 30 " x 29"

Should be:

Bottom = 96" x 30"
Front = 96" x 29.5"
Back = 96" x 29.5"
2 Sides 29" x 29.5"

This accounts for 1/2" glass

Bottom + front/back (1/2" + 29.5") = 30" height
Front + Back + Side (1/2" + 1/2" + 29") = 30" width

 

[Pharaoh]

They are idiots and have it where the front, back, and sides don't rest on the bottom glass. Dumb, dumb, dumb. The sides, front and back, should all reset on the bottom glass.



Should be:

Bottom = 96" x 30"
Front = 96" x 29.5"
Back = 96" x 29.5"
2 Sides 29" x 29.5"

This accounts for 1/2" glass

Bottom + front/back (1/2" + 29.5") = 30" height
Front + Back + Side (1/2" + 1/2" + 29") = 30" width

Curious as to your rationale for not thinking this is an acceptable way to build? I've seen many tanks built this way, including mine.

 

[nolapete]

Curious as to your rationale for not thinking this is an acceptable way to build? I've seen many tanks built this way, including mine.

When you have the bottom with the glass around the outside, the entire weight of anything you put on the bottom of the tank is exerting force against the seal around the bottom glass.

When you put the glass resting on the bottom glass, only water pressure exerts force on seal. The seal is compressed instead of stretched. A compressed friction bond is stronger than one that is stretched.

I've seen a lot of people driving on the wrong side of the road. That doesn't mean it's correct either.

 

[Satan's Goldfish]

^Agree^

Heard of tanks working like that too with no issues. Is there reason one would be better than the other?

 

[Satan's Goldfish]

Ignore post, question answered while writting it!

When you have the bottom with the glass around the outside, the entire weight of anything you put on the bottom of the tank is exerting force against the seal around the bottom glass.

When you put the glass resting on the bottom glass, only water pressure exerts force on seal. The seal is compressed instead of stretched.

I've seen a lot of people driving on the wrong side of the road. That doesn't mean it's correct either.

 

[MaddMaxx]

When you have the bottom with the glass around the outside, the entire weight of anything you put on the bottom of the tank is exerting force against the seal around the bottom glass.

When you put the glass resting on the bottom glass, only water pressure exerts force on seal. The seal is compressed instead of stretched. A compressed friction bond is stronger than one that is stretched. Do you mean compressed by the weight of the glass? Otherwise, its still stretched, just with a shear force (typically worse I think). Anybody know if silicone does better in tension or shear loads?

I've seen a lot of people driving on the wrong side of the road. That doesn't mean it's correct either. I'm staying away from where ever you drive then...

.

 

[nolapete]

Either way, the glass/silicone/glass is a tension bond. Shear strength is going to be greater where the silicone is not stretched already by another force.

Their way, you have downward shear and outward elongation.

The better way, you have compression which keeps the silicone the most dense it can be and only outward shear on that friction/tension bond.

I'm not a physicist, so I don't know the formulas to prove my point. I do however have 35 years of keeping aquariums and have refurbished many. I can tell you that the ones that last the longest are the ones built with the glass resting on the bottom.