Glass lined plywood tank, will this work?

[glasman]

So lets say i build a 400 or so gallon plywood tank from 3/4". If i line the inside with 1/4" glass and seal it up with silicone, think it would work? Not the viewing window, just to cover all the wood. I will use 1/2 or 3/4 for the viewing window. I ask this because i have a pretty much unlimited supply of 1/4" glass.

[rithunder916]

yes i believe the wood would support the glass just fine. However the only thing is that wood will naturally flex..glass will but not as much as wood. So if your planning on doing something like that, make sure to take that into consideration.


This would create a really cool effect :) if you say stained the wood, or used a furniture grade plywood...with the glass you could see the wood grain...

[ITHURTZ]

The glass will crack, both expand different and flex. Just paint the plywood

[WeedCali]

Im sure if your were to make a sturdy frame around the plywood, it wouldnt be as bad of flex.

[GMOB323]

i think sooner or later the glass will crack...possible fix reinforce the plywood with steel brackets in an x shape

[Bubbles123]

I've been thinking of doing this also. I've googled alot and most people think it won't work because of the different expansion rates. I haven't found anyone that has actually tried though.

[BoCoMo]

Is there a way to double up the 1/4" glass?

[glasman]

I could always add as many layers as needed, i wasnt so worried about the flex, i can make it stiff enough, i just wanted to hear some thoughts.

[WeedCali]

what if you lined the plywood with some 1/4 or 1/2" foam to give it some leeway?

[foolishfish]

Plywood in general is very dimensionally stable, but it will warp if one side is coated or covered and the other is not. Check out Nolapete's monster tank build if you want some good coating sources. If you try anything with plywood check out cabinet shop suppliers rather than the home centers. Wholesale vendors will have over sized sheets available, up to 72" X 144" for example and better grades as well. More plys for the same given thickness, better adhesives and fewer voids differentiate the levels of quality but so does the price.

I have an 8'L. X 30"H. X 2' W. sump made out of painted 3/4" BC plywood with an EPDM rubber liner that's about 7 years old but it always looked like crud 'cuz it didn't have to be pretty...just hold water.

BoCoMo brought up an interesting point about laminations though. You got me thinkin' before about it because of your tank bottom design. The only thing that had me worried was that even though you only use a little dime sized dab between the layers I was afraid that the viscosity of the silicone wouldn't allow it to flatten out enough when you lay the two pices together. The resultant void seemed worrisome but obviously it works.

It seems like it would be a real bugger to assemble but why wouldn't double layers work in place of many dollars a sq. ft. single thickness slabs?

I have built hardwood frame replacements for busted up plastic ones with good success. They are a little bulkier and have to be extremely well coated and sealed to prevent moisture absorption.
With all of that cheap glass available why in the world would you want to fool with wood. In the battle of wood vs. water, water always wins...eventually.

[glasman]

I just have a little more faith in wood and screws than i do in glass and silicone. Even though i have built around 300 tanks, i still cross my fingers everytime i water test a big one. Also, if my 1 year old were to bang a toy against the side of a plywood tank i wouldnt have any worries, not sure if i could say the same for an all glass tank of 400 gallons.

[CWO4GUNNER]

That's what resin is for. You want to see the wood like its covered by glass? Simply apply a purpose designed underwater boat resin for wood after staining. That's why they invented it.

[rithunder916]

If you were to re-enforce the plywood with something that is very rigid..say oak, i don't think it will flex enough to worry about it. as for expansion issues, i think it will be fine. I myself would make a 1x4 oak frame, with 3/4" plywood panels, and use 1/4 glass


Mike

[foolishfish]

I think I'd start by making friends with an engineer or a kid who gets A's in physics, just to get an idea of the loads that you'll be dealing with at full depth. Red oak, plywoods, southern yellow pine, they all have known structural properties that should be looked at along with the holding properties of the adhesives and fasteners used. Depending on how you frame it you'll have all sorts of compounding forces at work on the materials. Shear, compression and tension, dynamic and static loads, all limited by the strength of the weakest link.

Anything is possible as long as you know what the forces and loads are that you have to contain.

As for potentially catastrophic failures...
My son tossed a little plastic toy that hit our 30g. when he was just old enough to sit up on his own. Must have hit it just right 'cuz we were swimmin' in fish that night. 30 gallons of water can make a heck of a mess in the living room. I don't even want to think about 400.

[glasman]

I think I'd start by making friends with an engineer or a kid who gets A's in physics, just to get an idea of the loads that you'll be dealing with at full depth. Red oak, plywoods, southern yellow pine, they all have known structural properties that should be looked at along with the holding properties of the adhesives and fasteners used. Depending on how you frame it you'll have all sorts of compounding forces at work on the materials. Shear, compression and tension, dynamic and static loads, all limited by the strength of the weakest link.

Anything is possible as long as you know what the forces and loads are that you have to contain.

As for potentially catastrophic failures...
My son tossed a little plastic toy that hit our 30g. when he was just old enough to sit up on his own. Must have hit it just right 'cuz we were swimmin' in fish that night. 30 gallons of water can make a heck of a mess in the living room. I don't even want to think about 400.
Me either, i cant imagine trying to clean up 400 gallons of water and fish!

[CWO4GUNNER]

As far as a strait forward large 300-500 max rectangular wood aquarium with glass front viewing its not a big deal especially if you keep your height (water column down to 18" because its depth or piled up water that is exerting the greatest forces. An 18" column of water is equivalent to 1/10th the weight and pressure of the entire earth's atmosphere or 15 feet of water is 1 earth's atmosphere (ground to outer space) which is why your ear drums can rupture if you don't equalize the pressure is so great when diving.

Past 30 inches and you need to seriously consider abandoning a rectangle shape for round, a round container can handle substantially more water with less material and less supported structures. If I was going to build a very large free standing aquarium say 60 inches high and 50 feet across and 81 feet around and 41,000 gallons. All I would need structurally would be is piece of sheet steel 60" X 81' X 1/32" thick and 9 lag bolts, about 120 pounds of material with the viewing screen on top (air). Which could be built or disassembled in 1 day by two people at a cost of about $3000 and fit in the back of a mini pick up truck. The water pressure itself would provide most of the support to hold the walls in place, why large buckets are round not rectangular.

[CWO4GUNNER]

Oops! belay my last on water depth to atmospheric pressure, 30 feet not 15 equals 1 earths atmosphere. Somehow I remembered it as 15.

[foolishfish]

You're describing an above ground pool kit. I used to build swimming pools, among other things, and we did 100's of above ground pools each season. One in particular comes to mind 'cuz it gave me nightmares.

I had seen a video of a pool liner failure where 18,000 gallons washed out a stockade fence, which in turn struck another 24,000 pool in the next backyard down the hill from the first. The combined tsunami then washed at an angle across the back of the neighboring house and ripped a new porch clean off while blowing all of the basement windows out and flooding the house's basement.

We were asked to build a 54' X 28' oval above ground pool on a flat piece of ground about 10' in elevation above the owner's home. Our work was always dead level and complete but it's just one of those things that makes you a little extra careful, especially with the images of that video in mind.

The pool was essentially (2) 28' rounds flanged and bolted together. When complete it took (3) tractor trailer loads of water and a couple of days of sucking the owner's well dry to fill. When we got back to the plant there were three engineers eagerly awaiting our arrival. Not being used to such a greeting I was pretty curious myself what the occasion was.

They asked how the build went and were told that everything went smooth as usual. I swear the three of them all let out a collective sigh in unison. Then they told me that they weren't even sure themselves that it would work 'cuz they'd never tried one that big before. Can you imagine? These are the knuckleheads that design the darn things. I raised my prices that afternoon and doubled my insurance.

As flimsy as those pools look they are incredibly strong. An oval with a series of viewing windows is totally doable I'm sure. The only issues would be the proper flanging of the window to the wall and getting a plastic that is both U.V. stable and capable of replacing the structural properties of the steel that is removed. It wouldn't exactly be a thing of beauty but it would certainly work.

[BadOleRoss]

I built a tank like this several (20) years ago and it worked fine. I started by building an external frame out of 2x4s, lined the inside of the tank with 1/4" plexiglass, sealed all the the corners and filled it up. The tank measures 96x30x30 inside, the viewing window was 1/2" plexiglass. I had the tank for 3-4 years before I noticed a leak that was unrelated to the building method. If I was going to do it over agaain, which I will at a later date, I'd use liquid rubber from permidri http://www.permadri.com/pond-coat.html or maybe bluemax http://www.amesresearch.com/bluemax.htm.