Plywood only stand for a 180 gallon?

[vaypourus]

Thanks for the input all.

I studied for several years to become a mechanical engineer (ended up a System Engineer), and I did 3+ years of framing/foundation/construction work. I understand materials pretty well. I threw some ideas around with my brother (he's a rocket engineer) and we have no concerns with the compression strength of the plwood. Our concern was with torsion stress and as mentioned, the holes that will be cut for doors and access panels.

As has already been pointed out, the AGA stands and even some of the cheaper Perfecto stands are constructed of only pine 1x4 slats and particle board. I examined a 400 gallon cube aquarium @ my LFS and was completely amazed at the stand; it probably weighed only 80 pounds and utilized 1x4 supports even for a tank 2.5 times the weight of my 180.

After researching for most of the night (clinical insomnia sucks ) I've found that the only serious concern for an all ply wood stand is individual separation of the plywood layers due to the inherent moisture from the sump. As Mojoman had pointed out, the issue isn't with the strength of the plywood, but securing the plywood to itself. Glue, nails, and/or screws each have their own downfalls, and even gluing and screwing it together can only work so well with the face or ends of plywood. From what I have gathered, this is why actual solid pine is used by AGA and Perfecto for the actual support beams. It supports less weight than plywood (the compression strength of plywood is incredible), but will hold staples/screws/glue better without issue.

It looks like I will be building a hybrid type design; there will be both load bearing plywood shell and a internal reinforcing structure most likely made from 2x4s.

I'll get some initial design ideas up soon.

 

[dawnmarie]

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[CJH]

I threw some ideas around with my brother (he's a rocket engineer) and we have no concerns with the compression strength of the plwood.

I've found that the only serious concern for an all ply wood stand is individual separation of the plywood layers due to the inherent moisture from the sump. As Mojoman had pointed out, the issue isn't with the strength of the plywood, but securing the plywood to itself.

I have never built a stand using this method but went to an open house once that had a 110 gallon visible through a family room wall. I went into the mechanical room where the tank was located and was surprised to see it being help up by two very inexpensive cabinets. Cabinets were 1/2" particle board with a face frame. Granted they were screwed to the wall (but not into a corner) but they were holding up the tank at that time.

So yes, it will work, but you already know that.

As far as delamination, I would recommend a high-ply and void free plywood. I like the Russian or Finnish "Baltic Birch" plywood that you can normally find at cabinet supply yards. It comes in 5x5 sheets and has a Cryllic stamp of some sort in one of the corners.

I believe either the Russian or Finnish version is made with waterproof glue but I'm not 100% sure about this. I would research this yourself.

If you need 4x8 sheets for dimensional reasons then I would not (repeat, WOULD NOT) use the baltich birch sold in 4x8 sheets in some of the larger home improvement centers. This is a nice product but nowhere near the quality of true Baltic Birch and is known to delaminate, even without exposure to moisture.

There are two 4x8 sheet good products that are as of high quality as BB or even higher. One is ApplePly and the other is EuroPly. Both are very expensive.

As far as glueing plywood together "face to face", the best way is with epoxy and a vacuum bag. Short of that, weight the pieces down on a FLAT surface as best you can.

 

[Conner]

I am picking up a 220g (72x30) acrylic tank this weekend. The stand that comes with it is 2 pieces of plywood sandwiched all the way around (sides and top). I believe each piece of plywood is either 3/4" or 1". I'll have to measure once I pick it up. But I didn't see any additional bracing, it was just a box made out of plywood, with trim added for looks.

 

[john73738]

Properly build an all plywood stand will be more than strong enough. Having said that I do not have the confidence in my abilities to build one that is why I am I am building a 2x4 framed stand for my tanks. By doing this you can use cheaper 2x4's for the frame, and skin it with 1x4" ply or even 1/8" paneling. You will find that the stand will be strong yet you can keep the cost down.

 

[wamkiss]

Being a mechanical engineer you know that it is the quality of hte craftsmanship which dictates if the stand will hold. The shodiest do it your selfer over enginers to compensate for their confidence in their ability. If you really need to save 30 bucks and you feel confident about putting your head under 1400 pounds of tank with your stand then go for it. As long as the support is plumb there should be no problem. My freind built a stand for his 400 gallon Tenecore out of compressed wood, and its swollen from getting wet...its scary as hell. If his tank is still up im shure you wont have problems with plywood

 

[vaypourus]

Cost is only part of the issue; I may be moving in 6 months, and I don't want the stand to weigh as much as the tank .

Additionally, I need as much room under the stand as possible; I am building a sump using a 50 gallon tank, and I will need additional room for supplies, my mealworm breeding setup, and the algae scrubber under the stand as well. I know these all sound like minimal issues, but part of the issue is that this stand will someday be converted into a nice reef setup (when I can afford that 500 gallon Tenecor ). When that day comes, I will really need as much room as possible. Adding a bunch of 2x4s on each side reduces my available space by 7 inches in each direction.

 

[Conner]

As far as weight issues, I think that my 2x4 stand covered with 1/8" ply weighs less than an equivalent all ply stand would... Those 3/4" plywood sheets aren't light. I guess they may come out about even, but I would think the ply stand might actually be heavier, especially if you have to add any internal framing just the firm it up.

Plus, it was cheaper for me to use 2x4's skinned with 1/8" plywood, rather than an all plywood stand made out of 3/4" ply.

Just my .02, either way you go I'm sure it will be strong enough.

ps. I do understand about available room inside the stand. 2x4's will cut into that, but if you design it right, it shouldn't be too much of a problem, I'd think.