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Discussion Starter · #1 ·
I'm building an aquarium stand frame out of 2x4 poplar (1 3/4x3 1/2) and using Baltic birch 18mm plywood to skin it and for the bottom. The top will likely be 1 1/4" hard maple.

With regards to the floor of the stand (where the equipment sits), it seems most people notch the plywood to fit around the inner upright supports. Wouldn't it be easier to just screw the plywood onto the base frame (i.e. no notches) and then screw the outer frame uprights into the plywood? This is how they do it with subfloors in homes and they use OSB for that, so I'd imagine a piece of 18mm x 13-ply Baltic birch should be able to handle the weight.

The only real difference I can see is that you wouldn't use the 4 inner uprights that connect the tops. Most designs seem to use those for lateral support to prevent rocking but wouldn't the 18mm plywood skin (glued, screwed from the inside, and nailed with 15ga brads) be sufficient?

This stand is for an ADA 90-P, which I believe will weigh under 500 lbs with water and Yamaya stones.

Is there anything I'm missing or should consider?

Thanks!
 

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I think I need a sketch to picture how you are planning on doing it.

Are the uprights going to run past the plywood and to the ground? I wouldn't do this because it will limit the amount of space on your shelf

Are the uprights going to rest on top of the plywood? Normally I wouldn't do this because you wouldn't have a good connection between the base and the uprights (screws going into end-grain don't hold much) - But you said you are skinning with 18mm Baltic birch - if you have the outside faces covered with BB that should give enough strength to the connection.

-Justin
 

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I'm always into over kill when supporting 500 pounds of water in a living area. I would use angle bar screwed into the vertical supports and the top. What else would work as well would be to use 1/2-3/4 inch OSB for the back which should be attached to the top and the sides.
 

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Discussion Starter · #4 ·
Thanks for the reply Justin.

Here is a very crude diagram. I'll put together a SketchUp diagram when I get a chance.



I'll be using pocket screws for fastening the uprights to the base or, in the case of laying the plywood first, directly into the plywood. One question might be the screw holding strength of poplar versus 13-ply Baltic birch plywood. The lack of inner uprights (non-load bearing) might be a concern if the aquarium were to receive a bump, but I'd imagine the plywood skin would be sufficient to prevent movement.

Notching out the bottom plywood around the inner uprights isn't difficult but I find my jigsaw a bit sloppy which may result in minute gaps around the supports. Not a huge deal for some, but it'd drive me nuts. :) I guess I'm just curious as to whether there would be a real difference in structural rigidity by not using the inner supports and screwing into the plywood versus the poplar base. I can't see any difference being too significant, but I'm not an engineer so it never hurts to get a second opinion. :)
 

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Pixel Prestidigitator
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The difference is balloon framing versus platform framing.
The "legs" in the balloon framed stand will run from the bottom of the tank to the floor.
That allows you to screw the base framing and top frame to the legs with face to face joints. If you skin the stand though it won't matter much.
 

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Personally I wouldn't do this. You brought up that they do this when building houses. They do but it is normally done when building prebuilt, cookie cutter houses. These houses usually settle a lot when they are built becuase the plywood, usually OSB, compresses over time. A well built house has the subfloor cut so that the footer sits directly on the joices. When building a tank stand the last thing you want to happen is have settling. When a tank stand settles it can become unlevel and cause the tank to leak or worse explode. Personally I build my stands so that the supports go straight to the floor
 

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Best practice is to run the vertical (post) all the way to the floor, but with the skin and deck being Baltic birch, I think you will be okay. I wouldn't do it with OSB due to the compressibility of OSB, as has been mentioned. I think you definitely need the skin to help distribute the load from the vertical to the base and provide additional stability to the connection between the post and the base.

-Justin
 

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Pixel Prestidigitator
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Personally I wouldn't do this. You brought up that they do this when building houses. They do but it is normally done when building prebuilt, cookie cutter houses. These houses usually settle a lot when they are built becuase the plywood, usually OSB, compresses over time. A well built house has the subfloor cut so that the footer sits directly on the joices. When building a tank stand the last thing you want to happen is have settling. When a tank stand settles it can become unlevel and cause the tank to leak or worse explode. Personally I build my stands so that the supports go straight to the floor
That is not true. Most stick built houses are platform framed. It's actually safer in the event of a fire. And every house settles. Mine is a concrete floor with a stem wall foundation and it too has settled a bit.

I wouldn't build a stand this way because of the stresses involved in such a small area. Houses are built with a sill plate and a doubled top plate. I doubt the stand will be built like a wall is and will therefore lack a walls strength and stability.
 

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Discussion Starter · #9 ·
Thanks guys. I'll post up a few designs later and see what you think.

It still blows my mind that something like an ADA 90cm wood cabinet, which appears to use 3/4" panels, can support something like a 90-P (450+ lbs with water/hardscape). I guess the solid wood - or plywood if that's what they are using - is strong enough to support the weight but the lack of supports to prevent shifting if the tank is bumped or even just the water sloshing around during a cleaning seems odd. Perhaps the glued and screwed plywood panel at the back is sufficient to prevent side-to-side motion?
 

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Pixel Prestidigitator
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Thanks guys. I'll post up a few designs later and see what you think.

It still blows my mind that something like an ADA 90cm wood cabinet, which appears to use 3/4" panels, can support something like a 90-P (450+ lbs with water/hardscape). I guess the solid wood - or plywood if that's what they are using - is strong enough to support the weight but the lack of supports to prevent shifting if the tank is bumped or even just the water sloshing around during a cleaning seems odd. Perhaps the glued and screwed plywood panel at the back is sufficient to prevent side-to-side motion?
A cabinet built correctly can take a lot of weight. It's all a matter of how you construct it. The cabinets I built for my library system hold way more weight than a tank yet they are nothing but 3/4" plywood with face frames. But none of my carcasses are built with a plain butt joint. I use a tongue and dado on all of it and the cabinets are self squaring. Not only that but I can lift them up in a test run without them falling apart. No glue at all.
With a cabinet structure the back panel can be something like a door skin and while it is thin adds a ton of strength and will prevent racking when attached correctly.
 

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I wouldn't build a stand this way because of the stresses involved in such a small area. Houses are built with a sill plate and a doubled top plate. I doubt the stand will be built like a wall is and will therefore lack a walls strength and stability.
I think it's best to have a horizontal base and top frame that is based on the dimensions of the tank, with the upright supports between. This creates a larger footprint to spread the load stress out and supports the tank all around instead of just on the ends. On larger tanks additional uprights between the ends reduces the load carried by the top frame and end supports.

I guess this is kind of similar to wall framing. You could consider the base frame the sill plate and the top frame the top plate. If you put a plywood "skin" or other type of exterior (face frame with frame and panel ends for example) you provide additional stability.

As you state it's not good to have all the stress in a small area.
 

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Pixel Prestidigitator
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I think it's best to have a horizontal base and top frame that is based on the dimensions of the tank, with the upright supports between. This creates a larger footprint to spread the load stress out and supports the tank all around instead of just on the ends. On larger tanks additional uprights between the ends reduces the load carried by the top frame and end supports.

I guess this is kind of similar to wall framing. You could consider the base frame the sill plate and the top frame the top plate. If you put a plywood "skin" or other type of exterior (face frame with frame and panel ends for example) you provide additional stability.

As you state it's not good to have all the stress in a small area.
A lot will depend on the floor the tank is going on. If concrete I would run the legs to the floor. But I'd use half lap joinery.

I take that back. I'd use 3/4" plywood and build a real cabinet.
 

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Discussion Starter · #13 ·
This stand will be placed on ceramic tile against an outside wall. My refrigerator on the other side of the room (against a different wall) is around 400lbs and sits on 4 small wheels. Going to work on some plans now. So much to consider, but I'm trying not to overthink it as I tend to be a little OCD on projects like this, which maybe isn't a bad thing considering the result of a failed stand. :)
 

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This stand will be placed on ceramic tile against an outside wall. My refrigerator on the other side of the room (against a different wall) is around 400lbs and sits on 4 small wheels. Going to work on some plans now. So much to consider, but I'm trying not to overthink it as I tend to be a little OCD on projects like this, which maybe isn't a bad thing considering the result of a failed stand. :)
I was referring to what was the subfloor. Wood or concrete. Tile is more like a floor covering. Like carpet or CVT.
 

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This stand will be placed on ceramic tile against an outside wall. My refrigerator on the other side of the room (against a different wall) is around 400lbs and sits on 4 small wheels. Going to work on some plans now. So much to consider, but I'm trying not to overthink it as I tend to be a little OCD on projects like this, which maybe isn't a bad thing considering the result of a failed stand. :)
The consequences of overbuilding are a lot easier to deal with than underbuilding. A little more time and money spent vs. stand failure. Don't want to even think about it. Peace of mind is a good thing.
 

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Discussion Starter · #16 · (Edited)
After looking at various designs, here is what I've come up with so far:

(* the top in the images below should have edge banding, but it doesn't, oops *)





Quick overview:

- The base is 2x4 poplar (1 3/4" x 3 1/2") and I'm going to cut it to match the slight slope of my floor which should result in a level platform for the cabinet carcass to rest on.

- The base will be attached using Kreg screws from underneath.

- The cabinet panels, bottom, and top, and doors will be 3/4" (not undersized), 13-ply Baltic Birch BB-grade plywood.

- The cabinet panels will be assembled using Kreg screws, cabinet screws, and Titebond III glue.

- Front valence piece is 1x4 poplar (3/4" x 3 1/2") and will be glued and brad nailed (15ga) to the cross brace.

- The sides of the cabinet will be joined together with same 2x4 poplar as the base using Kreg screws.

- All exposed plywood edges will be edge banded with solid 1/4" birch, conveniently sold by my local lumber yard.

- The cabinet doors will have a 1x2 poplar strip on the inner edge to allow me to route a concealed finger recess for opening the doors.

- The cabinet doors have an 1/8" reveal top and between them.

- Will be using Blum soft-close hinges (reduced noise/shock for the fish).

- Can't remember what you call the latches where you can simply press on the door to release it; they make a little click then pop the door open slightly (which will expose the concealed recess for opening the door.)

From everything I've read over the past week and after examining numerous images of ADA and Green Aqua stand designs, this seems like it will be more than sufficient to support an ADA 90-P.

Thoughts and suggestions are more than welcome. :)
 

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Good plywood can withstand plenty of weight straight down as long as there is another support member on the inside corners, like a simple 1x1 screwed and glued, or on the outside like a vertical 1x in the same poplar. This prevents sideways deflection if the tank is knocked or the unit is not true vertical. The shorter the section, the less deflection. If you look closely I did both, but the outside was for a look and covered the screws. Vertical 2x4 on the inside corners is plenty of support for 500lbs and will not compress a good multiply birch core. If you're concerned, make a square frame using the 2x4s with the bottom members full width and glue the square to the inside of the plywood, spreading out the point load along the bottom horizontal member sitting on top of the plywood sitting on top of the platform. You can then refer to this as "operation overkill"
 

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Thoughts and suggests are more than welcome. :)

Looks like a solid plan. Maybe think about adding a couple stiffeners to the top running front to back so that the plain plywood is only spanning 12" in that direction. I did this on my own stand because I didn't want to give the top any room to flex with a frameless tank. Sounds like you know what you're doing and have a pretty good start to a plan.


-Justin
 

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Discussion Starter · #20 ·
Good plywood can withstand plenty of weight straight down as long as there is another support member on the inside corners, like a simple 1x1 screwed and glued, or on the outside like a vertical 1x in the same poplar. ...
I really like your stand. I was admiring it while doing research on what to build and how to do it; found links to it via a Google image search (at least I think it was your stand). In the end though my wife felt that style would be too ornate for our kitchen, which has simple euro-style cabinets, etc. I also really like the simplicity of the ADA style cabinet. But if I was going to build a show piece, I'd definitely do it like yours. Very nice work! Absolutely love the recessed panel look on the sides. :proud:
 
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