Can pond liners, think glass, etc. be used in building plywood tank?

[toffee]

I happened to have a large sheet of rubber pond liner that used to be the 3000g pond, and have access to cheap 1/4" sheet glass or thin acrylic sheets.

If I want to build a 2x4 framed plywood tank with only one viewing side, can I leverage any of the above? I am thinking of something like a 120"x30"x36" (lxwxh) with a viewing area of 96"x 30".

Thanks for helping.

 

[leg89]

of all the above, the glass thickness is the only issue.

got check a glass calculator, and you'll see that you'd need more like 1/2" glass (just say that quickly, go verify yourself) but 1/4 is def not thick enough

 

[ITHURTZ]

Built my 180 gal with pond liner and acrylic window. Tmw I am putting in 2 acrylic windows to my 270gal plywood pond liner tank. I expect in 2 weeks to have it up and running.

 

[Alexxxxsv14]

Built my 180 gal with pond liner and acrylic window. Tmw I am putting in 2 acrylic windows to my 270gal plywood pond liner tank. I expect in 2 weeks to have it up and running.

kool post pics

 

[ITHURTZ]

This is the only pic I took when I started the 270gal, not much to see there

Here is the 180, bascially a test to see if it could be done. I did it, so now I am going to do it on my larger tank, but it will look much better

 

[lilsuper2335]

well do you plan on making that viewing area a little bigger? almost like looking out a prison cell with the way the bolts are setup. no leaks thought so thats cool

 

[ITHURTZ]

The 270gal the windows are 21x43", viewable is something like 40"x19" x 2 windows.

 

[toffee]

Just some random thoughts :

1. In a normal glass or acrylic thank, the glass or acrylic has two functions:
   • Structural integrity
   • water proofing
   • therefore the bigger the tank, thicker the material
2. In a plywood tank, those tasks are handled separably. The plywood box for structural and epoxy etc for water proofing. The added complication for plywood is the viewing side or sides.
3. By separating these two functions, in theory one can build a thin walled glass or acrylic tank inside a plywood structure, on the viewing side, use a thicker material.
   
   In my case, I only need one viewing side, so four thin (3 side+bottom) plus one thick side
   
   Would this appraoch crack due to different coefficient of expansion between the wood structure and acrylic/glass structure?
   
   Coefficient of linear expansion for:
   • Tempered glass: 9 x 10-6 m/Mk
   • Plywood: 6.1 x 10-6 m/MK
   • Acrylic: 10 x 10-6 m/MK
   If my math is correct, for a 3 meter (9ft?) tank under an extreme 100 deg F temp swing, an acrylic inner tank will out expand the plywood outer tank by 0.2 inches.
   
   A thin layer of foam?

 

[redm18]

Just some random thoughts :

1. In a normal glass or acrylic thank, the glass or acrylic has two functions:
   • Structural integrity
   • water proofing
   • therefore the bigger the tank, thicker the material
2. In a plywood tank, those tasks are handled separably. The plywood box for structural and epoxy etc for water proofing. The added complication for plywood is the viewing side or sides.
3. By separating these two functions, in theory one can build a thin walled glass or acrylic tank inside a plywood structure, on the viewing side, use a thicker material.
   
   In my case, I only need one viewing side, so four thin (3 side+bottom) plus one thick side
   
   Would this appraoch crack due to different coefficient of expansion between the wood structure and acrylic/glass structure?
   
   
   Coefficient of linear expansion for:
   • Tempered glass: 9 x 10-6 m/Mk
   • Plywood: 6.1 x 10-6 m/MK
   • Acrylic: 10 x 10-6 m/MK
   If my math is correct, for a 3 meter (9ft?) tank under an extreme 100 deg F temp swing, an acrylic inner tank will out expand the plywood outer tank by 0.2 inches.
   
   A thin layer of foam?

I'm not saying that it can't be done this way but I would say that about 50% of the people that begin looking into plywood tanks think of this same idea and I have yet to see a tank built this way. I think its because it does not work. The glass will be exposed to extreme preasure at imperfections in the wood or movement in the tank or temp fluctiation. I think thin acrylic is also has these problems plus it warps.

 

[mrunlucky07]

Some of the koi people have been building indoor ponds with liner/windows. Here is one from a recent build, it is the 10th one he has done. Here is the link:

http://www.koiphen.com/forums/showthread.php?t=101931&highlight=spa&page=2