I’ve had tanks of several sizes, and have discussed stands with many other fishkeepers. My conclusion is that the vast majority of people “overbuild” their DIY stands. I’m no carpenter or engineer, and I can appreciate the thinking of “Why use 2x2 when you can use 2x4? Why use one 2x4 when you can use 2?”
But I have spoken with many folk who seem to know what they are talking about and doing, and have been convinced that folk consistently underestimate the strength of plywood. As you note, most commercial stands are built like crap, yet I’ve never had or heard of one failing. Enough 2x4s to hold a 30g won’t be that heavy, but I had one friend build a massive stand to support 125g, and he needed something like 5 guys to help him move it from his workroom to his family room.
I have no doubt that 2x2s and 3/4" ply would be sufficient for a 30g. Just put sufficient thought into how the load is borne and distributed. If you are worried about moving it, go with the 2x4s, and you could use 1/2" ply.
Heck, if you want to overbuild it, screw the screws, and go with carriage bolts!
Skinning the back and sides with ply will provide excellent cross-bracing, by the way. Just make sure that you screw into your frame frequently enough to allow it to do so.
Because I’d like something fairly attractive. I have a lot of nice wood furniture, and metal shelving would look, well, kind of like it goes in the garage.
This may be my favorite reply yet. : )
So 2x4s and, say, 3/8" ply is lighter than 2x2s and 3/4" ply? (I’ve no idea how weighty ply is)
I think BF is considering not exactly doing a frame, but “hinging” the panels together with 2x2s, screws, and glue at the corners all around- or something like that- I’ve really had to pull out of this emotionally because I’m far too much of a worry wort to be anything but irritating to him. (at least I know this) so my description is probably inaccurate.
His position all along has been: “Look at the crap they sell to support those 30 gallons. Anything I build will beat least 2x stronger.”
My thinking was mainly that weight isn’t a HUGE consideration for a stand with a footprint for a 30. So it really doesn’t matter what you choose to frame and clad it. Ply gets considerably more expensive - and heavier, each thickness you increase. We’re still talking under $50 for lumber. But if you go 2x4s and 3/4", not only is that way overkil, but that would be a ridiculously, unnecessarily heavy stand.
Screwing together 2x4s is just about the easiest construction method there is. Heck, ask any stoned college student who just cobbled together a loft! I was just saying my strong opinion is that for 300# you don’t NEED that much strength. The way I see it, if you want to try anything other than barebones drunken college student construction, you can explore more elegant options without the 2x4s - and have no worry about structural failure. On the other hand, you can go with the 2x4s and be comfortable that an earthquake could knock down your house and the stand would remain standing!
When you (or your BF) designs it, you want to make sure that you have a frame which supports the entirety of the tank’s perimeter, and structure which evenly and directly transfers that weight to the floor. Construct the footprint in a manner that evenly distributes the weight.
As I’ve said before, tho, a 30 really isn’t all that heavy, so a lot of the structuire you add will be for your peace of mind, rather than strictly necessary. Search the many fishkeeping sites - you’ll find tons of examples of DIY stands of all types and sizes.
Do not use carriage bolts! You can never get them tight! The more you try to tighten them, the more the nut or bolt head will crush into the wood.
Use regular bolts and nuts, but instead of washers, go to a metalworking job shop and have them shear some 1/4" steel plate the size of the narrowest width of your lumber square, (providing that’s where you are installing the fastener). Drill a hole in the center of these plates just large enough for whatever size bolt you are using to clear.
You should be able to snap off the bolt before you ever significantly crush the wood.
I was joking about the carriage bolts - way overkill for a project of this size. But I imagine a bunch of deckbuilders would be surprised to hear your criticism of them!
Heck, might as well lap the joints, glue them, AND screw them. This is a whole 300# this wood is going to be supporting!
Take a look at your average kitchen table chair… It will hold 300 pounds of shifting, leaning and moving weight without issue. It will handle all kinds of abuse without exploding or sinking through the floor boards. It will do all that and more because it is well engineered but without needing some of the over the top suggestions in this thread!
The shear strength of a common #8 screw is somewhere around 1800 pounds. Per screw. The compressive resistance of a common 2x2 is likely somewhere up in the 10s of hundreds of pounds. The racking resistance of plywood is ridiculously high.
Nothing wrong with overbuilding, heck, that’s my middle name, but in the end, it’s only 300 pounds. To put it in perspective, a 36" Sony WEGA CRT TV weighed in at 245 pounds or so… Did the stands of the old school big TVs need carriage bolts or some of the other suggestions? Nope, knockdown fasteners and particle board was all that kept them up and it worked fine.
I say this as a guy who dovetailed his shop cabinet drawers… over the top isn’t an insult but still much of the advice is over the top.
Ugh. I hate carriage bolts. You can’t ever get them quite as tight as you want, and God help you if you ever need to back them out again. Use a real bolt with a real hex head that you can keep still with a second wrench. Countersink it if you’re that worried about how it looks. But good god, I hate carriage bolts.
Thinking outside the box. What about a workbench that has drawers in it? Something that will handle the weight no problem, you can store stuff in it, and it rolls around?
I am interested in a tank that is eight feet long x 2 ft x 2 ft.
I have read about using 2 x 4s. Or 2 x 6’s spaced out 8 - 10 inches apart… but I was wondering if it is possible to use 2 x 2’s stacked on top of eachother then use 1/2 inch plywood on outer and inner walls , sandwiching the 2 x 2’s in-between the plywood . That would create a solid 3 inch. Or so wall all the way around.
I think that’s probably overkill, but other than that, it should work.
One thing to keep in mind - the platform should be perfectly flat on top. Any tiny bump will create a stress point on the tank. So, make the top surface a continuous sheet of MDF, and make sure it’s smooth and level.
am interested in a tank that is eight feet long x 2 ft x 2 ft.
I have read about using 2 x 4s. Or 2 x 6’s spaced out 8 - 10 inches apart… but I was wondering if it is possible to use 2 x 2’s stacked on top of eachother then use 1/2 inch plywood on outer and inner walls , sandwiching the 2 x 2’s in-between the plywood . That would create a solid 3 inch. Or so wall all the way around
Thank you for responding. I sent the second time on the SD website . And I wasn’t sure if that would be technically overkill. Or not. I was just trying to save a little bit of space instead of using 2 x 4s but keeping as much strength as I could
