Will It Hold?

[Murphy]

Hi all, I'm building stands for my fishroom and would like to stack 100gal tanks two high. Tanks are 48"Longx24"Widex18"Deep I need to know, will the design hold the weight of two 100gal tanks?

[daninthesand]

I would say that YES it will hold. My stand is very similar except its longer and made of 2x4's only. And no notches (cut outs) in the vertical supports. The shelves have 3/4 inch plywood glued and srewed to the top of the horizontal supports. 1/2" styrofoam on top of that. If you have the room for height, and you want to use 2x6 construction, i'd use 2x6 for the horizontal instead. And 2x4 for the legs. Don't bother notching unless you really have to. Bolting and glueing the shelf to the legs will be plenty strong.

My stand holds two 50's and two 30's (all tanks are 36 inches long) on each shelf, all tanks facing with the end forward. That works out to 18hx61wx36d, which is 170 gallons on each shelf. Mind you I do have a middle set of legs, but mine is almost twice the gallons....

I'd recommend using pressure treated wood since rot might be a problem down the road, especially at the bottom where the leg hits the floor. Water will collect there and rot the legs.

But your design looks good to me, and will easily hold 200 gallons. One other thing. In my case the basement walls support the side to side movement of the stand, so there is no worry about lateral stress on the stand. If yours is going to be free standing, I'd suggest some kind of diagonal bracing across the back (eg from the top left to the bottom right corner) and sides for extra security from distortion.




Daniel

[limige]

hockey pucks dan hockey pucks!!!!!
can't beat them, keep the legs off the floor, also i'd suggest painting it to reduce rotting possbility.


this is how i did mine

[daninthesand]

Hockey pucks EH! Do you know where I can get those in Canada? ???


;D

Daniel

[Chris]

Hey Murphy

Your stand looks good, but the side to side movement is an issue. I mentioned this in another post, plywood is about the best thing in my opinion to stop the side to side movement. In your case I would put it on the back of the stand. This will tie two corners together, stopping the side to side twist.

Good luck

Chris

[RichieE]

With that span I would bolt or screw (sister) another 2x4 behind the cross piece to prevent sagging over time. I'm not sure if its necessary. I tend to over do it when it comes to 800 pounds.
Consider building it in such a way that the bottom tank is bumped out a few inches for easier access. Its not necessary and takes a little more time and materials but I found it to be worthwile. It also makes the stand a little more stable. HTH Rich

[ronrca]

What I did with my rack system is put another 2x4 in the center also which then would make it 3 2x4's instead of only 2! Then, put some 3x4 plywood on top of the 2x4's to further increase the support!

If you only use 1 tank per shelf, you should not have sag problems! (If you do, your tank would crack) The problem though is when using 2 or 3 tanks per shelf!

Id also recommend putting in a cross piece in the middle of the shelf to prevent the 2x4 from twisting!

[lauris]

It is my understanding, supposedly confirmed by a structural engineer, that the ONLY weight bearing portion of the sketch above is the vertical 2X6. Further, that notching substantially decreases the strength of the vertical. And, that the maximal strength is achieved in the verticals when the narrow side is out. I have no hope of graphing this, but the strongest support would be bolting a cross piece to the broad sides of 2X6's.

The cross pieces (running the length of the tank) are unnecessary from a structural standpoint. They do help with preventing the stand from spreading, but I have found (with two-high 75 gallon tank stands) that the same anti-spread effect can be achieved by only running a cross piece under the back edge of the tank. Once the tank is on and filled, ain't nothing spreading.

Leaving it out in the front increases the access to the lower tank and allows it to be higher off the floor. In my opinion and experience, there is no reason to brace across the length of the tank, or to put plywood on those braces to make a "shelf" for the tank, this does nothing to increase the weight bearing properties of the structure and only increases costs and uses up valuable space, all weight is borne at the ends by the uprights.

For the side to side "rocking" motion that occurs, I have found that two 1X10's across the back will take care of that, the 10" (actually 9.5") width prevents the rocking and is easier for most people to handle than plywood (which also works well). Take care to put the 1X10's where you wont block access from the rear into the tank.

There are many ways to skin a cat....but in my relatively vertically cramped basement I need to maximize clearance and have had no problems with leaving out the horizontal bracing. I would note that the above would relate only to stands where tanks are being supported at each end, obviously other structural issues are implicated when tanks are narrow end out or two 24" wide tanks are put above or below a 48" tank.

[Smokey]

lauris, thanks for the input. You brought up a very important point.
When 2 0r 3 tanks are on the same shelf. The vertical supports now carry the dead weight . The horizontal supports carry a live weight.
If the horizontal supports "flex" downward, the tanks Live weight becomes a very important issue.

Smokey