Wood frame weight support carpentry question
 

I'm building a wood stand for an RO water tank (cylindrical plastic garbage can), the weight will be about 350 lbs full of water. The stand will be about 3 feet high and the base will be about 2 feet by 2 feet square give or take. I have minimal carpentry skills but am trying to teach myself.

The question is, what dimensions of lumber to use. I don't want to overbuild it, I could make a 2 x 4 frame that would probably hold over 1000 lbs. I want to use the narrowest wood that will do the job, for efficiency but also for lightness. Also what sort of design would hold a load the best?

I was thinking of a rectangular cage made of 2 x 2's (four vertical 2 x 2's one at each corner, with a square of 2 x 2's on the base and at the top) , with either plywood or 2 x 2 cross-bracing to keep the thing square, and a flat plywood square on top to distribute the load. I was thinking I would put this together with glue and wood screws.

Is there any hard data on what weight different dimensions of lumber will hold, and which frame design will hold the most weight?

Sounds like it will work. Overbuilding is always good IMO.
Can you screw the structure you build to the wall so it can't move, twist or lean? That would make it solid and worry free.

This would be perfect and provide more than enough support. I would use plywood rather than cross-bracing however. You may have a hard time finding straight, non-twisted lengths of 2x2. Personally I'd use 2x4's. I've built dozens of temporary tables like this for work and they are able to handle hundreds of pounds of fittings... plus my fat @$$ during lunch.

guessing from picture in this post of a tank on a stool, your 2x2s would work (wouldn't use a stool though as could imagine the legs opening up), but in RC SW mixing stn thread, 2x4 the norm.

Are you planning on having it upright or horizontal? I have 2 of the plastic barrels on stands in the basement used to collect RODI waste water. One is upright, the other is laying on it's side. Both stands they are on are built using mostly 2x4 lumber. For the one laying on its side, I used two 2x6 sections with an arc to match the barrel curve cut into them. At the narrowest point, the 2x6 are 1 & 3/4 inch and this seems to support an almost full barrel no problem. I also added a strip of old carpet padding on the arcs of the 2x6. The barrel is never completely full, since the RODI waste drains into the top hole & would overflow if I didn't turn things off in time. Lose a bit of capacity this way, but it allows me to use the existing holes in the barrel without drilling more. The screw caps for the barrels have a threaded knock-out, so it's easy to plumb a valve to them.

Here's a pic. Doesn't show the stand(s) unfortunately. Time for some more photos I guess. The upright blue barrel doesn't get used much since I haven't drilled holes in it & when I do use it, I have to siphon or pump the water out, which is a pain.

https://tsl4pa.bl3302.livefilestore....97a.JPG?psid=1

Thought I had some documents on my hard drive regarding wood strength, but unable to locate. I'm sure it's available on line somewhere, that's where I got it. There can be a significant difference in wood strength based on species, i.e. hardwood vs softwood, clear, knotty etc.

It will be upright. Can't attach it to a wall.

It might also help you to drill pilot holes so that you don't split the wood.

That's important when using screws in wood of any species.