# DIY Plywood Aquarium Question



## im2smart4u (Dec 7, 2010)

I was wondering if anyone had ever heard of someone making a tank out of plywood and glass without the window method. What I am trying to say is, have you ever seen/heard of a tank with a plywood bottom and back (and maybe even sides) but with a solid piece of glass in front. So the front glass would connect to the plywood bottom/sides just like it would to the glass sides in a regular tank.

The reason I ask is that I have an idea in my head that I might try to build soon if it is feasible. I was thinking that a solid glass front and sides would make it seam nice like a regular tank. Hopefully it can be done to make it look like a nice all glass tank (with no top rim) when done (since you can't see the back and bottom anyway).

Any thoughts or suggestions are welcom. If you want, I could try to draw out what I have in mind. That might make it easier to see what I am thinking (be warned, though, my art skills are non existant).


----------



## Svynx (Nov 8, 2010)

Absolutely. A lot of people have made plywood tanks. These are saltwater tanks, but the construction is the same. Good threads:

http://reefcentral.com/forums/showthread.php?t=1663472

http://reefcentral.com/forums/showthread.php?t=1749114


----------



## im2smart4u (Dec 7, 2010)

The difference between these and what I want to build (apart from mine being much smaller) are that those are built using the window method. I would like to build mine just like you would build an all glass tank (with no top rim), but having the bottom and back "panes" made out of wood. These tanks use a wood front panel, with a hole cut in it and the glass applied to the inside like a window. They are nice tanks, but don't fit what I want to do.


----------



## Svynx (Nov 8, 2010)

Ok, I get it. The only problem I see is actually connecting the full glass front to the plywood bottom/sides. I just don't see enough holding strength. The reason for the window is because the pressure pushes the glass against the plywood, making a better watertight connection.


----------



## Wasserpest (Jun 12, 2003)

How do you intend to connect/glue the glass to the wood Smarty? :wink:


----------



## im2smart4u (Dec 7, 2010)

I am hoping someone else has tried this before so I know it will work. The bottom of the front panel wouldn't be an issue. I can use a wood trim on the outside to help hold the bottom edge. It is the top I am worried about. I am sure I could do it with some bracing, but I would prefer it if I could keep it completely open top. It would look much better. When I get home after work, I may try to draw it out and post a picture of my idea. I think it would make for a neat tank.


----------



## jwm5 (May 9, 2010)

i dont see any way of successfully doing what you want. you could theoretically do something with a "low profile" frame made of metal on the front or even the entire thing, but you will need something to support the glass and secure it to the material that the rest of the tank is made of


----------



## Hoppy (Dec 24, 2005)

The success of this idea would depend on the strength of the adhesive joint at the adhesive to wood and the adhesive to glass interfaces, and on the thickness of the glass vs the size of the glass. More important, I think, is that it will not resemble an all glass tank, because the wood sides will likely be at least 3/4 inches thick, which will be far thicker than the glass one would expect to see on the sides. It will look like a wood tank with a glass front. So, it seems best to go with the "window" design instead, but use furniture grade wood for the front frame, something that would take some very good engineering work to make work and look good at the same time.

Of course a hybrid wood/steel design could be used, with a steel frame around the front glass, that hides the edges of the wood sides, and prevents the sides from being pushed apart by the water pressure. Now, you are into a cost likely to be far more than the cost of an all glass tank.


----------



## sailnut (Nov 26, 2010)

If you have a router it would be easy to route a grove in the side and bottom panels, fill the grove with silicone and insert the glass. 
If you used high quality plywood and cabinet type joinery (no butt joints) I think you would end up with a very nice tank.
However you would still end up with a framing (thickness of the plywood) around the glass. Butt gluing the glass to the front would be a very risky undertaking.


----------



## Hoppy (Dec 24, 2005)

This is why routing a groove and inserting the glass into it would be a bad idea. Plywood isn't very strong in shear stress.


----------



## drlower (Dec 14, 2010)

i agree with hoppy on shear strenth and also dont like the router idea as glass wood and glass will expand and contract at different rates and if the glass is captured in a groove there could be failure.


----------



## im2smart4u (Dec 7, 2010)

The picture below is the idea I have. Excuse the bad 3D. I am not very good and I did this real quick. You should be able to get the idea though.

What I would like to build is a corner tank. All glass tanks that I have seen can be built with no frame. They are being held together entirely by the silicone. I was thinking of stealing some glass from a 40 breeder for the glass pieces. The front and back of the tank would become the two front sides, and the normal sides would stay there (using other tanks and dimensions could maybe work as well). 

Anyway, I figured if it works for all glass, why wouldn't it work for a glass and plywood hybrid. That is if the silicone will stick as well to the plywood. If it doesn't stick as well (and I am assuming it isn't) but still sticks fairly well, I would still think this could work. By making the bottom and sides just a little longer than needed, I could screw/glue a piece of trim like wood to the plywood outside of the glass (the picure doesn't show the framing). This would create a frame around one side and the bottom of the sides, and a frame across the bottom of the front panels (since the front panels are attatched to glass sides, it should stil be just as strong there as a normal tank). The only issue, I think, is whether or not the water pressure would push the whole glass assembly loose. Again, the bottoms would be held in, but I just don't know if the silicon holding the side pieces would hook to the back wood well enough to keep the whole glass assembly from popping off.

I figure (with no proof to back it up) that the design should work no matter what if braces were added from the middle corner to both the back walls, but I would prefer that there be no brace at all, for ease of access and to keep light from being blocked.

SO, this was really long winded, but I wanted to make sure that you could see what I was talking about. Any comments/suggestions would be appreciated.


----------



## VaultBoy (Nov 11, 2010)

That would be a cool looking tank...

i think you would be better off building it all glass, you could theoretically use timber if you fibreglass and epoxy coated the timber parts first and then machined the edges with a router or plane, to a perfect smooth edge then treat them as you would glass with just the silicon to hold it together...

but i wouldnt do it...

let us know if it does work.


----------



## Svynx (Nov 8, 2010)

The only way I see it working is if you had plywood coming off the back pieces by about a few inches. That would give the corner strength, and would also give the glass a parallel connection vs a perpendicular connection (which I don't see working at all). Would make things a lot safer. You could then add some bracing in those corners to help with the pressure since you want to go rimless. Fiberglass/epoxy the wood and you might have a winner.


----------



## Gatekeeper (Feb 20, 2007)

VaultBoy said:


> That would be a cool looking tank...
> 
> i think you would be better off building it all glass


Agreed. The two outside corners appear to be a serious weak point. You need to frame them in somehow and I don't see a practical way of doing that.


Good Rule of thumb: Two different materials, twice the chance of failure.


----------



## Hoppy (Dec 24, 2005)

The corner tank would fail because the wood back pieces would be pushed back by the water pressure, with nothing to hold them in place. If the epoxy idea would work, and I doubt that it would, you might have enough strength in the epoxy to glass bond to hold it against the water pressure. This would be an idea to test outdoors for a few months before even thinking about putting it anywhere that much water would be a problem. If I wanted to test the idea I would make the tank twice as high as I wanted it to be, then if the joints held up, they would be plenty strong at half the height. For example, take the two glass pieces and turn them 90 degrees, so the tank is as high as the length of the glass pieces, and make a column tank, with the two back pieces made of wood. Filling it with water would be a proof test of the wood to glass joint. 

Have fun, and take lots of photos!


----------



## im2smart4u (Dec 7, 2010)

I think, with the right bracing, that I can pull it off, so I think I want to try it. I may regret saying that later, but I won't know unless I try. If I do it, I will definately take pictures of the process. I may even start a journal. 

Of course, with losing some of my fish in my other tank I am kind of bummed right now. I lost the 2 most expensive fish in the tank, 2 double red agassizis, and a double red cacatuiodes looks like it might be next. :frown:


----------



## sailnut (Nov 26, 2010)

Hoppy said:


> This is why routing a groove and inserting the glass into it would be a bad idea. Plywood isn't very strong in shear stress.


 Agreed but its a lot better then a butt joint. Also I am suggesting that the vertical panels be similarly routed. With an adequate lip and depth (.5?) and hi-quality multi core plywood everything should be fine


----------



## redfalconf35 (Feb 24, 2008)

sailnut said:


> Agreed but its a lot better then a butt joint. Also I am suggesting that the vertical panels be similarly routed. With an adequate lip and depth (.5?) and hi-quality multi core plywood everything should be fine



While better than a butt joint, the lip would have to be enormous to hold up. Remember that plywood is just sheets of wood glued together, so you're going to have hundreds, if not thousands of lbs of pressure on a .5" strip of glue. The routed area would fail spectacularly


----------



## sailnut (Nov 26, 2010)

All glass frame-less aquaria are butt jointed and held togeather with silicone which does not adhere all that well to glass. I am suggesting that the be tank constructed of 3/4 inch plywood (bottom sides and back ) these elements are joined by some type of routed joint. 

Then the glass front is epoxyed into a groove routed into the aircraft quality plywood using slow setting epoxy. This would be by far a stronger arrangement the an all butt jointed tank.


----------



## Wasserpest (Jun 12, 2003)

sailnut said:


> All glass frame-less aquaria are butt jointed and held togeather with silicone which does not adhere all that well to glass.


This reminds me of the old saying about the grain of salt to be taken with all you read on the interwebs.

Hoppy's graphic really drives the point home. While the lip can be made larger, and a thicker plywood sheet could be used, I wouldn't risk this on a larger tank.


----------



## im2smart4u (Dec 7, 2010)

Hoppy said:


> This is why routing a groove and inserting the glass into it would be a bad idea. Plywood isn't very strong in shear stress.



My plan would be to just have the glass on top of the wood, not in a groove. Then a 1-2 inch piece of wood could be put on the outside of the glass on the lip. This piece could be glued and scewed into place, which would make it stronger than just a groove in plywood. Then run a bead of silcone on the inside and maybe even the outside. This would give the tank a heavy, fairly bulky bottom brace, but hopefully would make top bracing not needed. I could do the same thing where the side panes meet the back, except the wood trim would go along the bottom of the tank and up the back side where it attatches to the wood back.


----------



## im2smart4u (Dec 7, 2010)

This picture shows what I mean. The brown lines, horrible drawn with Paint, would be a trim piece that was scewed and glued to outside lip of the bottom (and side) piece of plywood. The same thing could also be done on the inside. (I don't know whether it would be better to screw those in from the bottom or from the top.) Then with the wood coated in epoxy and all the edges siliconed up, I would think that it would be fairly strong (as least to outward pressure at the bottom). All the wood would be painted black. The bottom would appear "clunky" but the top would be open. 

Does anyone think this would work? Also, remember this tank would only be around 16 inches high. I definitely wouldn't trust this to support a tall monster tank.


----------



## Hoppy (Dec 24, 2005)

First, do some research on the strength of a silicone bond to wood compared to the bond to glass. If it is a strong bond, then the idea should work well. If not, it won't. Consider what surface treatment the wood will have before bonding to it, also. Some finishes, such as epoxy might be much better than others, such as polyurethane. That's how an engineer approaches such a problem - part of it, at least.


----------



## nalu86 (Oct 19, 2010)

why don't you just use fiberglass, steel frame and acrylic glass, should work perfectly for your corner tank.


----------



## sailnut (Nov 26, 2010)

im2smart4u said:


> This piece could be glued and scewed into place, which would make it stronger than just a groove in plywood. Then run a bead of silcone on the inside and maybe even the outside. This would give the tank a heavy, fairly bulky bottom brace, but hopefully would make top bracing not needed. I could do the same thing where the side panes meet the back, except the wood trim would go along the bottom of the tank and up the back side where it attatches to the wood back.


I am a long time model plane builder and have a lot of experience dealing with force setups such as we have here..

You really want to grip the glass on the sides. By doing that you are directly countering the high pressure which the glass (essentially trying to push out and rotate outward along the bottom edge) places on the bottom panel when it is the sole or major support.

With model planes this force setup is almost always controlled by supporting the left and right sides of the force plate (glass here) via front and rear doublers. Any concave/convex VERTICAL cupping is dealt with by a single doubler on the bottom at the rear of the plate. If properly done the this type of structure will absorb a great deal of punishment. 

For what it worth I have never seen a quality piece of ply wood split or shear parralel to the glue up layer... never.

If I was to do this I would make the sides of 3/4 inch aircraft plywood with a 1/2 inch deep grove whose width is slightly more then the thickness of the glass. I would make the back and bottom parts from 1/2 inch ply and join them to the sides with dovetails cut with my router. I would machine a 1/4 inch deep grove in the bottom piece to retain the glass.

The entire assembly would be glued up with slow drying epoxy. .

Such a tank properly finished would be incredibly strong and rigid.


----------



## Hoppy (Dec 24, 2005)

When you start talking about 3/4 "aircraft" plywood, you are jacking up the cost, and soon you have to wonder why you are building a tank this way. And, plywood of that quality isn't sold at Home Depot, nor at most hardwood stores. This is also something to question when you start talking about a steel reinforced plywood structure - the cost is something to stop and wonder about.

I have no doubt at all that a plywood tank can be built, if cost is not a concern, that would be just the corner tank you are looking for, and plenty safe. But, why do it that way?

Those who have built plywood tanks have been reporting over and over that plywood tanks become economical only for very big tanks. And, for those, there are proven building methods using Home Depot quality plywood.


----------



## MrK (Oct 27, 2010)

Just a thought...you could use acrylic instead of glass as this could be glued/sealed and mechanically fastened (screws) along all the wood to glass seams making for a very strong joint


----------



## shane3fan (Nov 2, 2009)

MrK said:


> Just a thought...you could use acrylic instead of glass as this could be glued/sealed and mechanically fastened (screws) along all the wood to glass seams making for a very strong joint


 
You could do that with glass as well. Car windows are bolted or rivited in all the time. Getting the holes in the glass is the tricky part


----------



## sailnut (Nov 26, 2010)

Hoppy said:


> When you start talking about 3/4 "aircraft" plywood, you are jacking up the cost, and soon you have to wonder why you are building a tank this way. And, plywood of that quality isn't sold at Home Depot, nor at most hardwood stores. This is also something to question when you start talking about a steel reinforced plywood structure - the cost is something to stop and wonder about..


Of course you are right. However a plywood tank can be made in any proportion and/or capacity you chose. Properly built its sure to be stronger then any glass and arguably an acrylic tank.

Using quality material and joinery does much to reduce the possibility of a leak or catastrophic failure. Butt joints are an invitation to disaster! I am against overbuilding so I am suggesting 1/2 ply for the bottom and rear panel .

Personally I do not believe that plywood is the appropriate material for any structure that's going to be immersed in warm biologically active water. Whats the difference between a plywood aquarium and a wood boat?

An interesting possibility is to laminate with epoxy, a foam panel between 2 sheets of heavy fiberglass cloth. Sometimes strips of carbon fiber for stiffening are worked into the lamination schedule. Such a panel is strong, light relatively cheap and can be cut and joined easily. This method of construction is very popular with advanced model plane builders for the reasons above.

I think that acrylic is also a more suitable material but it requires more skill to work and is expensive.


----------



## tusk (Jan 30, 2006)

My $0.000000000002 having built a plywood tank.......

Cool design, gonna be a PITA to build. You are going to have to have some type of frame along the glass (0.5 - 1" would make me very very leery). You're also going to have to do some bracing for the rear for a corner tank. That you can do successfully, ask me how I know  I don't think you'd need a frame at the top if you could seal it properly, from my understanding though, that is WAY easier said than done though.


If you're dividing up a 40 gallon, that's more than 80 gallons you have to contain....... that is a TON of water on the floor. You can't skimp.

Honestly if you're serious about a tank like that, see if there are any acrylic guys around and see what they could do for you. Otherwise give it a whirl, don't skimp anywhere, be prepared to open your wallet as DIY plywood sounds cheap in the beginning but to do one right costs a bit.


----------

