New Plywood Stand.

[Fishess]

Hello. 4 years ago i had build my first ever stand out of plywood. But now i'm in need of a new stand.
My main question would be: How thick plywood would i need to build this type of stand? (Stand and Aquarium is 1to1 size in images.)
My aquarium size is 60Lx40Wx55H CM ~130liters (35gallon) In future i may go 200Liters (55gallon) long..
Some info: Stand will be 100Lx60Wx110H CM. The top and bottom will be bigger, so screws have more place to hold onto side panels. Back panel will hold everything together. The aquarium will not be sitting on the corners. That's why i have added those red 2x4" at top.. So aquarium weight doesn't bend the plywood top. The red planks are 2x4" wood going from one side to other side that will be glued/screwed into sides of plywood. From outside of plywood with two big, long, thick screws per red 2x4". In general everything will be screwed/glued together.
I need the front/middle open, because i will be putting steel/metal cabinet inside it. (The white box. I know i can build DIY cabinet with door, etc.. But i need that cabinet in the stand - so don't ask..) That's why i have added those red 2x4" at top.. So aquarium weight doesn't bend the plywood top. Top plywood is see true.

I'm also thinking about adding "L" brackets under the 2x4" red logs. So it holds stronger.. Otherwise there will be holding only 2 screws per side of red log. Should i add them?

So how thick plywood should i use?
Some images of the stand:

 

[Reefing Madness]

 

[TX_REEF]

why not frame with 2x4 then skin?

 

[ShakeyGizzard]

why not frame with 2x4 then skin?

Probably cheaper, and also way stronger

 

[ShakeyGizzard]

This is a 2x4 framed and skinned stand.

 

[DIYreefer]

Probably cheaper, and also way stronger

Actually, when built correctly a plywood stand is very strong, probably more so than a 2x4 stand. Reason being the cross grain pattern in the makenup of plywood. It will also allow for more space inside the stand as well.

The term I'm looking for eludes me, but when you place the weight along the edge of plywood it's going to be much stronger than a 2x4 stand of equal construction. However, this is really just splitting hairs as either would be plenty strong enough for what OP wants to do. We're not talking about a 1,000 gallon tank here, lol.

 

[DIYreefer]

This is a 2x4 framed and skinned stand.

That looks nice.

 

[ShakeyGizzard]

1 2x4 can support 1000 lbs. , price wise and strength wise. cant beat 2x4. plywood has its uses. But using plywood to support weight were the chance of getting wet is high , keeps me from using it to support weight.

 

[ShakeyGizzard]

That looks nice.

Thank you, here's a shot of the sump, 40 breeder tank, 20g long sump. Stand interior painted with exterior house paint to water proof.

 

[Fishess]

why not frame with 2x4 then skin?

If i wanted to build it like that, i would have asked about 2x4 stand...
Like i said - i need open frame so i can put a cabinet inside it. (2x4 are too wide for me.) And screwing 5 walls together are way simpler and easier to do.

 

[Fishess]

FYI: I'm gonna also glue it and use many big screws.. At the end i'm gonna to paint it. (2layers) Not worried about water damage. (Also i'm gonna put countertop on the stand itself.. So it would look nicer.) I have been using plywood stand for past 4 years. I just need new design with open frame..
I'm thinking about using 1.37inch (35mm) birch plywood.
Will it be strong enough for 55gallon? Am i fine with 35mm plywood, if i'm gonna build it like in images. (The stand will look like that.)

 

[twentyleagues]

If i wanted to build it like that, i would have asked about 2x4 stand...
Like i said - i need open frame so i can put a cabinet inside it. (2x4 are too wide for me.) And screwing 5 walls together are way simpler and easier to do.

Reef builders (Jake Adams) did a video on a shop that builds plywood stands good idea on how to do it and what not to do. My 180 sits on a plywood stand no issues. Mine was made by a local guy that builds cabinets and stands/canopies for my lfs.

 

[twentyleagues]

This is a 2x4 framed and skinned stand.

It looks nice. Appears all the weight is only supported by screws? Safer to put vertical beams under horizontal to support weight.

 

[Gill the 3rd]

Plywood is plenty strong for what you want to do. I would use 3/4" not just for the weight, but if you are screwing the panels together it gives you more "meat" to screw into. You risk blowing out the side with a screw if you use 1/2".

 

[DIYreefer]

It looks nice. Appears all the weight is only supported by screws? Safer to put vertical beams under horizontal to support weight.

It looks like the bulk of the weight is distributed to the corner 2x4s, the cross beams aren't really doing much. Fortunately, they put some plywood across the top to help distribute the weight more evenly. This is not a design I would use, but I'm sure it works just fine.

 

[DIYreefer]

Plywood is plenty strong for what you want to do. I would use 3/4" not just for the weight, but if you are screwing the panels together it gives you more "meat" to screw into. You risk blowing out the side with a screw if you use 1/2".

Agreed. 3/4" is the right choice. I would only use 1/2" if it were a very small tank (10g) for the same reason you suggested.

 

[twentyleagues]

It looks like the bulk of the weight is distributed to the corner 2x4s, the cross beams aren't really doing much. Fortunately, they put some plywood across the top to help distribute the weight more evenly. This is not a design I would use, but I'm sure it works just fine.

Same. Trust me I've built many.

 

[fishyjoes]

I have a stand for a 55 gallon tank (4foot by 1 foot by ~20 inches) that was built using 3/4 inch (about 2cm) plywood.
I bought this stand back in 1997 and it's still fine today (it was used for a few years, then stored for many years, and has been in use again for the last two years)

 

[ShakeyGizzard]

It looks nice. Appears all the weight is only supported by screws? Safer to put vertical beams under horizontal to support weight.

look closely. the legs go from top to bottom, the corners of the tank sit on the tops of the legs. all joints are glued and screwed. You can take the screws out and it would be fine. Tight bond 2 joints are stronger than the wood. the horizontal 2x4 would only support any sagging. Stability is key, excessive movement will cause weakness.

 

[DIYreefer]

FYI: I'm gonna also glue it and use many big screws.. At the end i'm gonna to paint it. (2layers) Not worried about water damage. (Also i'm gonna put countertop on the stand itself.. So it would look nicer.) I have been using plywood stand for past 4 years. I just need new design with open frame..
I'm thinking about using 1.37inch (35mm) birch plywood.
Will it be strong enough for 55gallon? Am i fine with 35mm plywood, if i'm gonna build it like in images. (The stand will look like that.)

The whole water damage thing is a bit misleading. It would take A LOT of water, and over a significant period of time to do any real damage. People fail to realize/remember that the vast majority of high productions stands are actually made out of veneered MDF. Which is FAR less tolerant of water than plywood is. They use it because it's cost effective and it works. It's not the best choice, IMO, but yeah, even MDF would be sufficient if designed/built correctly.

The reason why I stopped doing 2x4 stands is because you are putting a whole lot of faith into one piece of wood, with one grain pattern. Some one else posted a claim of a 2x4 being good to hold 1,000 lbs and I think that is incorrect (I think what I've seen in the past is 500 lbs, but I digress), but with plywood you get exceedingly enough strength for most applications along with the peace of mind of knowing that if there was any weakness in the wood itself, it would very likely only be in one ply. With a 2x4, it's one 2x4, and if it's bad the whole thing goes boom. I also quit using 2x4's because it creates a stand that is overly bulky and doesn't allow for much room for a sump underneath.