3' span

TheSinisterSOB · Aug 30, 2014

Hello,

I'm getting ready to build an 8'x3'x3' plywood tank, and need some feedback/info on the stand.

I will be using multiple 2x6 studs for each support on the outside perimeter of the tank, but my concern is will a 3' span require additional support in the middle of the tank?

The initial plans were for a 4' width, however the placement of the tank in the garage and my wife's parking skills drew too many safety concerns. So the tank is going to be 3' wide, and I wanna make sure to have enough support, but also enough room for the sump.

Thanks in advance.

BearFish · Aug 31, 2014

Well, the simple answer is yes, but like any engineering project it depends on how you build it. But, a 8'3'3' stand will have about 4,500 pounds of water weight. The weight on the bottom of the tank is 1.3psi, so in a 3' by 3' region you will have a load of 1,700 lbs. So, 3 to 4 2x6's will more than carry this weight. But, what really matters is how much deflection or sag occurs in the span as it can crack your glass or start a leak. The stiffness (young's modulus) of a grade 2"x6" is 1,400,000 psi, thus one board caring 1,700 lbs will sag ~1/32". 3 2x6 will sag ~1/96". (By the way this is just the engineering part, you get water or steam the numbers will change greatly)

I would suggest you use 3 to 4 2x6 with 2x4 sandwiched in between ply wood (running width wise) on top of the 2x6's to get that overbuild DIY feel.

Best of luck

Drstrangelove · Sep 1, 2014

I'd need a diagram or detailed description to make any comments. The tank has 2 middles underneath it...back to front and side to side, and it's not possible to tell which you are referring to in the post. In addition, 2x6 wood can be laid in multiple ways under a tank, including but not limited to: planks (1.5" tall) or support beams (5.5" tall) which are tremendously different.


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3' span

TheSinisterSOB

Gambusia

BearFish

Feeder Fish

Drstrangelove

Potamotrygon