Double tank stand for a 120 and 75

[DenisD]

Hey Everyone,

I am thinking of doing a double tank stand out of wood for the following 2 tanks which would go on in a basement with a concrete floor:

Tank SizeOutside Dimensions in Inches (L x W x H)Weight Empty and Full (lbs)
75 Gallon 49 x 19 x 22 140 850
120 Gallon 61 x 19 x 25 215 1400


I was thinking of using the following guide to make the stand:
http://ovas.ca/images/articles/darkdep-diy-stand/images/large/Murray_AqStand_0120.JPG

Could this stand work if the top shelfs were made out of 2 by 6's doubled up instead of 2 by 4's and without the 2 center legs as I don't want to obstruct the view and get in the way of the bottom tank?

The top shelf would be 40 inchs from the ground and the legs 2 by 6's.

Please let me know what you think.

Thanks!

 

[PDX-PLT]

I don't know if the stand in the picture would be strong enough as shown (or overbuilt, for that matter), but let's assume for the sake of argument that it is just right.

As a (very) rough guide, the strength of a beam is proportional to the square of the depth. So going from 2x4's to 2x6's, they will be (5.5/3.5)^2 = ~2.5 times stronger.

The problem is that your doubling the span by removing the center legs. Onlce again, as a rough, back-of-the envelop calculation, if you double the span, the beam needs to be 4 times as strong. So no, if you remove the center legs, merely changing the 2x4's to 2x6's will not compensate. You would need to go with doubled 2x8's to make it just as strong as the original.

As "real" structural calculation would mean evaluating shear, deflection, and beam strength, but the above rough calcs are good enough to see if what you want to do is reasonable.

 

[DarkSoul]

what about making "I" beams out of the wood? glue/screw it together.

how stong would that prove to be?

 

[Plecosterone]

Doubled 2x6 would be plenty. Most people "way overbuild" stands. The one in the link is an example of this overbuilding. First of all you don't even need 2x anything in a properly designed stand. Just look at any you can buy from the LFS. How many have LUMBER in them?. Properly designed particle board stands will hold up to 180 gallons no problem.

 

[DenisD]

Anyone else?

 

[DarkSoul]

Doubled 2x6 would be plenty. Most people "way overbuild" stands. The one in the link is an example of this overbuilding. First of all you don't even need 2x anything in a properly designed stand. Just look at any you can buy from the LFS. How many have LUMBER in them?. Properly designed particle board stands will hold up to 180 gallons no problem.

I have one for my 50 gallon. I paid $200 for it. it holds the weight just fine.
when my cat sneezes down the hall, the stand wobbles.
particle board is crap.

if my daughter or gf are doing something, and either trip, or just plain hit the tank, I could easily see it wobbling, and then collapsing under the torque.

Therefore, I will build my own stand, and I will do it using lumber.


btw, with the size of your tanks, you would only have 6" left on either side of the 75 gallon tank, under the 120.
If you had a longer 120, and/or shorter 75, OR built your stand alot longer, it might work out better.

 

[ataylor]

I ran through the loads on the beams both on the horizontal and on the vertical. Doubled up 2x6's is plenty fine for what you want to do, even with the bigger tank up top.

If your stand top ties in those 4 horizontal beams, it will be super strong(TM) at that point. You can also tie-in the doubled up horizontals with a carriage bolt or two so they share the load.

The floor will be fine as well, assuming it's at least 4" thick. I'm sure it is. Make sure you post some pics when you are done. Nice project!

 

[PDX-PLT]

what about making "I" beams out of the wood?

I beams are designed to make optimum use out of the material, by putting it where it is needed the most. Calculations for them are straightfoward, just as they are for rectangulat beams. 'probably overkill for somehting like this, though.

 

[Plecosterone]

I have one for my 50 gallon. I paid $200 for it. it holds the weight just fine.
when my cat sneezes down the hall, the stand wobbles.
particle board is crap.

if my daughter or gf are doing something, and either trip, or just plain hit the tank, I could easily see it wobbling, and then collapsing under the torque.

Therefore, I will build my own stand, and I will do it using lumber.

I did say "properly designed stands". The ones you buy from the LFS or watlmart are NOT properly designed. They are almost always missing any kind of meaningful lateral support, hence the wobbling.