# pressure on DIY aquarium walls



## Rick_Lindsey (Aug 26, 2002)

Is the pressure on the walls of an aquarium purely a function of water column height, or does total volume play in as well? I was just pondering a DIY "garage tank", 4x4 footprint, ~2' high stuck in the corner using the sides of a used 55gallon tank for the windows. There would be 4 times the water volume as the donor 55, but a very similar water column height. Should one be worried about that application of the glass?

Similarly, if one were to disassemble two used 55's and reassemble the front/back panes of both tanks into the 4 sides of a regular glass tank, but somehow figure out how to work that into a wooden top/bottom, would one need to worry about breaking glass or bursting seams? (though come to think of it one might need to worry about the expansion/contraction of the wood... might have to scratch that idea)

thanks,
Rick (the armchair aquarist)


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## cichlidfeesh (Apr 6, 2009)

I'm not going to say if this is safe or not but here is a little equation that might help you

P=egh

Pressure = (density of liquid)(9.8m/s^2)(height)


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## jwal (Jan 17, 2008)

If the water height is not more than 1-2 inches above the aquarium it was used for, I would probably assume it is safe to use.


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## Mcdaphnia (Dec 16, 2003)

Pressure on the walls is totally a function of water height. But twist on the glass is increased by the width of the viewing area, so in very long tanks, thicker glass is used to offset the increased chance of stress cracks, and especially breakage during assembly. In your case you are using short panels. If you frame each one, no problem, but it will still look like two tanks side by side to an extent. If you laminate them together, you will invite stress problems from twisting pressures.


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## Rick_Lindsey (Aug 26, 2002)

Thanks, guys! McDaphnia, I'm not sure what you mean by laminating the panels together? I was considering two scenarios :

1) "standard" DIY plywood tank that's 4feet square and 2feet deep, with two window on adjacent sides of the tank made from the front and back panel of a 55g aquarium.

2) more of a "hybrid" plywood tank, using the front and back panels of two 55g tanks as the 4 aquarium sides... siliconing those panels together in a normal glass aquarium fashion, but then using plywood for the base and top brace/lid.

Is the latter the laminating you're talking about, or are you talking about taking 2 4 foot panels and laminating them to get an 8 foot panel?

if option 2 sounds like it wouldn't have stress issues, are there reasonable ways to attach a wood/epoxy/fibreglass bottom to an otherwhise glass tank?

thanks!

-Rick (the armchair aquarist)


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## Rick_Lindsey (Aug 26, 2002)

There's a (very) rough cartoon showing the two scenarios I had in mind... I suspect they may be worth more than a few words 

-Rick (the armchair aquarist, who apologizes for drawing option (2) on top of option (1), but hopefully it will be clear which is which!)


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## padlock 08 (Jul 31, 2008)

i dont know what your going to be keeping in this tank, but it's going to situated in a corner, yes? if it IS going to be in a corner i would just use the one tank's 2 panels and a glass top for viewing on top, i think having the wood walls at the back would reduce any reflection of light which would take away from from the fish inside. if i was going to set this tank up i would make it 8 foot square and get rays or something that likes a wide, shallow tank


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## Mcdaphnia (Dec 16, 2003)

Laminating the way I was thinking about it would not apply to this tank, but often people consider making an 8 foot tank out of the pieces of a 55. In that case they may overlap the two pieces, or lap both with a small glass strip. That is the kind of lamination I was thinking about.

Just a thought. Many large antique aquariums were glass set on top of a stone bottom, usually slate. I see granite pieces much larger than 4' by 4' all the time. That would be one way to create a tank bottom, and by the time you consider the paint, or fiberglassing, and other costs of a plywood tank bottom, Granite would be more in line cost-wise than at first glance. And granite is in style!

If you do put this tank in a corner, part of the tank will require a four foot reach. I hope you know some pro basketball players.


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## BillD (May 17, 2005)

Curious as to where granite would be cost effective. Around here granite counter tops (as an example) run between $50 and $90 a square foot.


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## padlock 08 (Jul 31, 2008)

occelated rays could be kept in this tank at its current footprint, id still go plywood with 2 windows, leave the top open you can still view the fish, i dont know what i was thinking


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