tank design questions for the physics minds

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philhawk

Feeder Fish
MFK Member
May 17, 2006
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bellevue, ne
i like most of us here am contemplating the construction of a truly monster tank. i have decided to go with a plywood tank to save some money (hopefully, i hear tales that in the end it costs the same).

intended dimensions would be 120x48x30

i know that the greatest amount of pressure is exerted at the bottom of the tank and exponentially decreases as you travel up the wall.

so the question is: by decreasing the size of the viewing window and bringing it up from the bottom of the tank wouldn't it follow that you would not need as thick of glass to resist the pressure?

i know that the glass is the most expensive single piece in the aquarium so if i could reduce the thickness of the glass i could save some serious coin.

the pic shows my meaning, plan on building up rock towards the front so that the fish cant hide right at the front below the glass (the only disadvantage of the idea that i can think of.

all thoughts and comments are welcome
thanks
 

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also i have seen a person on here with with a plywood tank where they some how used pond liner rather than epoxy and or fiberglass. yet they still had a viewing window in the front the tank was aprox. 350 gallons. and using pond liner seems like a really easy way to seal the tank perfectly.

i haven't been able to find any info on how this is properly accomplished more info would be great.
 
yes you can raise the window if i was u id raise it so that the bottom of the window is 2' from top. all you would need is 15mm glass.
 
You are correct. An example is pouring a concrete dam -- The bottom is always poured much thicker than the top. Also, I agree that the only disadvantage is reducing the viewing area.

Just get glass a thickness that will hold the pressure for the depth where the glass starts.
 
what about increasing the viewing area by creating an up side down triangle of glass so that the surface area of the glass was decreased it would leave you a small viewing area at the bottom still and the viewing area would increase as it went up i believe that a smaller surface area of glass would also reduce the thickness of glass you needed , im not sure but i think it makes sense as far as physics is concerned
 
that wouldn't work because the pressure on the glass is the same in the middle as is is on the right and left sides, it is the depth of the water that increases the pressure
 
Hdeuce;2071445; said:
what about increasing the viewing area by creating an up side down triangle of glass so that the surface area of the glass was decreased it would leave you a small viewing area at the bottom still and the viewing area would increase as it went up i believe that a smaller surface area of glass would also reduce the thickness of glass you needed , im not sure but i think it makes sense as far as physics is concerned
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Intuitively I think that would work since the flexural force on the material would be less at deeper depths for a triangle but I would have to check with Roark's formulas to be sure. Also, to see if it would give any significant financial advantage.
 
I'm an mechanical engineering student, and we learned about hydrostatic force in calc. last semester. Finding the force on a panel of glass is just a simple integral. I actually wrote a simple program that calculates the force by knowing the width and height of the panel of glass. If you give me the measurements, I will let you know how much force in pounds will be exerted on the glass.
 
born2lovefish;2075134; said:
I'm an mechanical engineering student, and we learned about hydrostatic force in calc. last semester. Finding the force on a panel of glass is just a simple integral. I actually wrote a simple program that calculates the force by knowing the width and height of the panel of glass. If you give me the measurements, I will let you know how much force in pounds will be exerted on the glass.
Click to expand...

When you move on to materials you will learn about stress and flexural strength. This is where the size of the rectangle comes into play. If you are interested in that information, I can PM it to you but it is a bit deep for here.
 
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