Advice on Cinder Block/I-Beam Stand

[Khazmodain]

I'm going with a cinder blocks and steel I-beams (technically H-beams or wide I-beams) for my stand on an in-wall 400g. The tank is a 72x36x36 acrylic. I have 3 beams which are 72 inches long and are 6" tall x 4" wide (aka 6 x #12). The three beams will run parallel to one another supported on the ends by cinder blocks. I was originally planning on building a wooden 2x4 frame with support braces running perpendicular to the beams which would then have 2 sheets of 3/4" plywood on top of it. The tank would then sit directly on the plywood. I'm now wondering if I actually need the 2x4 frame or if I should just lay the plywood directly on the beams. If set directly on the beams there would be 12" gaps between the beams running the width of the tank. Is that too much unsupported space? I realize the plywood will help distribute the load but I'm still concerned.

Any thoughts from you structurally inclined people out there would be appreciated.

Thanks!

 

[dave.m]

You didn't mention the thickness of the acrylic or whether or not the tank is euro-braced at the top and bottom.

Dave.M

 

[Khazmodain]

3/4 inch acrylic except for top which is 1 inch. Top has two access holes cut into it.

 

[dave.m]

Probably this is okay but for the sake of surety it wouldn't hurt to sister a couple of 2x6"s to run between beams across the top of the blocks (perpendicular to the beams).

Dave.M

 

[anbosu]

I would just double the plywood and you should be good to go.

 

[Khazmodain]

That's good to hear. I'd love to be able to avoid the additional layer of 2x4 framing if possible.

 

[Khazmodain]

Also, if anyone has any thoughts on the cinder blocks being dry stacked vs dry stacked with cores filled vs mortared joints vs concrete/landscape adhesive I'm all ears.

Thanks!

 

[dave.m]

Have you done a Search on the string "i-beam" in this forum? I'm pretty sure there have been several tanks using I-beams as support here.

djm

 

[rygar]

why not find a mason to do a little side work for cash? Would take a lot of pressure off you. And if you gotta ask if 3 beams is enough, just get another one and take away the worry. I did 3 on a 48" deep tank, then added 2 more after the fact. would have been way easier just to get all 5 to begin with. I placed the plywood directly on the beams, then foam, then the tank. No cross bracing across the beams. Holding up so far.
Just be sure to coat the beams with something. I used undercoating.

 

[Khazmodain]

if you gotta ask if 3 beams is enough, just get another one and take away the worry. I did 3 on a 48" deep tank, then added 2 more after the fact. would have been way easier just to get all 5 to begin with. I placed the plywood directly on the beams, then foam, then the tank. No cross bracing across the beams. Holding up so far.
Just be sure to coat the beams with something. I used undercoating.

Lol good call. Not sure why that wasn't my original plan to begin with. That seems like a much better approach than building an additional wood frame to set on the beams.