Fish tank stand... metal and process choice

[Trip59]

Ok, so for this installment of stupid questions from Trip

New project, after the loss of one of my pets, my frilled dragon, I found myself with an empty 55 gallon tank, figured I'd set it up again as a fishtank, as well as a pair of 10's on a stand near it (hamsters are long gone).

Wife has been wanting a saltwater tank, so my wheels start spinning and a thought comes to mind, birthday present

Ok, so long story short, I decided rather than two tanks, I wanted invertebrates, she wanted more aggressive fish, I'm setting up a 75 on top, with a 55 below for an invert/refugium tank, and process the whole thing as a natural environment.

The 75 is occupied by a 3' monitor, who needs a bigger house anyhow, that'll be another project (8-9' long, 3' wide enclosure in my office, zoo style)

55 gallon metal tank stands have room for one above and one below, but not enough height. We had a 55 on top and 40 below (original plan). They're kinda wobbly, too wobbly to go for the 75 gallon version, most of which are shipped as slip together rickety crap.

I need to design a dual level tank stand, steel, for a 4'x18" tank on top and a 4'x12" tank on the bottom, flush on the front. I need to figure out leg and base arrangement and sizing, with a possibility of upgrading to a 75 on bottom, 90 on top later.

For reference, we're looking at a potential of 1000lbs per shelf, tank, water, rock, etc. (maybe a bit more on top if we go 90). Lots of weight.

So, what dimension steel, I was thinking of welding a box of square tube for each shelf, then heavy angle for uprights, with bases and adjustable machinery feet to level. Bracing on the sides and back for added rigidity, corner gussets perhaps?

Thickness will determine process, but it needs to be dead sure solid, multi-pass TIG?

Thoughts appreciated.

[everlastsupport]

I am not aware of any charts that will help there. But bigger is always better, and gussets and braces good too.

You can call the local metal/iron works guys and they will give you a size and thickness if you have the span, depth and weight on it. That's what I would do since you are talk a fair amount of weight. Or just over build it .

We lift 700-1000lbs things all the time with a hoist and gantry of square 1.5"x1.5"x3/32" (sides) and round bar on the top, no issues. About 4'+ wide (so not too wide).

[Trip59]

They won't give me recommendations... engineering, liability, blah, blah.

I'm thinking 3/16" wall 1.5" tube for the base boxes, and 1.5" x 3/16 or 1/4 angle for the legs. Might go 11ga 1" for the bases though, it'll be distributed fairly evenly over the entire perimeter, the corners I could gusset with 3/16 6" sided triangles to help the load. Stands commercially available are half that...

I've done, and seen them done out of 2x4 and 4x4 pine, that's an option too, but it looks bulky as hell, I'd rather go steel. Looking at the 55 stand I have, it's all angle, with crappy welds, nothing is thicker than 1/8" and there are no real gussets or braces.

How would you weld it? Appearance counts, either clean beads like a TIG or ground down other process...

[everlastsupport]

They won't give me recommendations... engineering, liability, blah, blah.

I'm thinking 3/16" wall 1.5" tube for the base boxes, and 1.5" x 3/16 or 1/4 angle for the legs. Might go 11ga 1" for the bases though, it'll be distributed fairly evenly over the entire perimeter, the corners I could gusset with 3/16 6" sided triangles to help the load. Stands commercially available are half that...

I've done, and seen them done out of 2x4 and 4x4 pine, that's an option too, but it looks bulky as hell, I'd rather go steel. Looking at the 55 stand I have, it's all angle, with crappy welds, nothing is thicker than 1/8" and there are no real gussets or braces.

How would you weld it? Appearance counts, either clean beads like a TIG or ground down other process...

What you stated should be fine, to me. Weird they would not help, I guess liability. The local guys here are friends. Make sure you brace it good. Funny steel is $.04 for scrap, but the price from 3/16" to 1/4" makes you still stick on the lower end.

TIG you can skip the grinding but take longer. But if a lot of joints, sometimes MIG and grinding is faster. Depends on the look you want too. I like ground like all one piece, others I know like the industrial/TIG look.

[Rambozo]

There is a small program called BeamBoy that will give you load, stress and deflection for all kinds of steel beams and shafts. Also a lot depends on how you design it. If you minimize shear loading on your welds, then you can get away with much smaller material under compressive loading, and the welds just hold it together. Of course it would be more stable with the heavier tank on the bottom, but I realize that's not what you want. With the right design you could do the whole thing with 1"x1"x.120" square tube and it would be capable of supporting 2000 lbs. with less than .020" deflection. 1.5" sq tube would reduce that even more. Since you have a distributed load instead of a point load you don't need to build it to take all the load in the center of the beams. With a fully welded unit, and bracing required will be minimal. I know visibility is very important to this project. Stability will largely depend on the floor this is placed on. If it's concrete, no problem. However, if it's wood or carpet, there will be a lot of load in a few small points and any motion of the substrate will be magnified at the top and make for something that feels unstable.