Will this stand be strong enough for 300 Gallons?

[Ben Pedersen]

I am planning on building a stand for my glass Marineland 300 Deep. The dimensions of the tank are roughly 6' x 3' x 27" tall.

I'm wondering if three 4" x 6" spanning 7' across the top and supported by three 4" x 4" on both sides for vertical support would be enough so I wouldn't need a center support. I really don't want a center support.

what do you think?

 

[4tanks]

Thays 1. 3 tonne just water without tank and rock I'd be putting a centre support in

 

[Sisterlimonpot]

I sort of did the same thing you did, but only wanted complete accessibility on one side (Back side). My 300 is 8' long and ended up using a 5"x9" glue laminate to carry the load so that I could get away with out a center support.

What I did was estimate total weight and then contacted one of the engineers from the company I was purchasing the glue lam from. told him the length and weight I had and he was able to tell me how thick the glue lam needed to be for the required deflection.

Don't quote me, but if I remember correctly the max deflection required to safely span 8' was 1/8". I opted to play it safe and went with 1/16" as my requirement.

I would do the same, especially since your tank is 6' and you're wanting to span 7'. which means that you're not supporting the edges of the tank with vertical supports directly underneath the corners.

I' sure there are engineers on the forum that can direct you better, but I wouldn't leave it to guess work. do the math.

 

[Sisterlimonpot]

Just to give you an idea:

here's the part in my build thread (Post 24)

Large Build - My rendition of 300

The waterproofing membrane made it here in perfect timing. I was almost at a stand still, This is the trowel that the company recommends to provide a thin layer of thinset in between to provide good adhesion. I went 4" up the wall, if any water leaks and collects on the step, it isn't...

www.reef2reef.com

 

[Sisterlimonpot]

And here's the thread where I basically did the same thing you did, asking the experts to help.

Calling all engineers!! - Reef Central Online Community

Calling all engineers!! Do It Yourself

reefcentral.com

 

[RocketEngineer]

I think you have way too much lumber for a modest size stand. I would not use 4X anything for a tank stand as it’s known for drying out and splitting down the road. For that size display, a 2x8 front and back top rail supported by 2x4s everywhere else is all the support you need and gives you pretty good access as well.

 

[Ben Pedersen]

I think you have way too much lumber for a modest size stand. I would not use 4X anything for a tank stand as it’s known for drying out and splitting down the road. For that size display, a 2x8 front and back top rail supported by 2x4s everywhere else is all the support you need and gives you pretty good access as well.

I would not be using treated lumber so I don't think drying and splitting would be an issue as the wood is already kiln dried.

 

[Ben Pedersen]

Just to give you an idea:

here's the part in my build thread (Post 24)

Large Build - My rendition of 300

The waterproofing membrane made it here in perfect timing. I was almost at a stand still, This is the trowel that the company recommends to provide a thin layer of thinset in between to provide good adhesion. I went 4" up the wall, if any water leaks and collects on the step, it isn't...

www.reef2reef.com

Nice stand... Mine will be set up as a peninsula so would like to have complete access from both sides.

 

[Ben Pedersen]

I think you have way too much lumber for a modest size stand. I would not use 4X anything for a tank stand as it’s known for drying out and splitting down the road. For that size display, a 2x8 front and back top rail supported by 2x4s everywhere else is all the support you need and gives you pretty good access as well.

I am trying to do this without a center support.

 

[Ben Pedersen]

I sort of did the same thing you did, but only wanted complete accessibility on one side (Back side). My 300 is 8' long and ended up using a 5"x9" glue laminate to carry the load so that I could get away with out a center support.

What I did was estimate total weight and then contacted one of the engineers from the company I was purchasing the glue lam from. told him the length and weight I had and he was able to tell me how thick the glue lam needed to be for the required deflection.

Don't quote me, but if I remember correctly the max deflection required to safely span 8' was 1/8". I opted to play it safe and went with 1/16" as my requirement.

I would do the same, especially since your tank is 6' and you're wanting to span 7'. which means that you're not supporting the edges of the tank with vertical supports directly underneath the corners.

I' sure there are engineers on the forum that can direct you better, but I wouldn't leave it to guess work. do the math.

It seems to be complicated math but maybe not. I think you would have to use calculus. And it has been 20 years since I did any of that.

It is easy to calculate load but less easy to calculate distribution of load as the load is not exactly over end supports. As the load gets further from the end support, I would guess there is a exponential drop off of load bearing strength until you pass the middle and it starts to increase again.

That is why I was thinking to use 4" x 6" with the 6" vertically supporting the load. The math that I don't know is how to calculate the span load bearing capability of a 4" x 6" with end support (4" x 4"), and the load distributed starting 6" from both sides. If I knew that, I could multiply it by as many 4" x 6" necessary to support the tanks weight.

But then there is the question regarding rigidity.. Would the support bow enough to cause the tank to deform and stress?

 

[RocketEngineer]

With a 2X8 header and 2X4 legs, you don’t need a center support and it requires half the wood.

 

[Sisterlimonpot]

With a 2X8 header and 2X4 legs, you don’t need a center support and it requires half the wood.

Can you provide the math and supporting information that aided you in arriving at that conclusion.

 

[Ben Pedersen]

I have noticed that many manufacture tank stand have very little support but hold the weight fine. However, I do want to make sure that whatever I build will not end in disaster.

 

[RocketEngineer]

DIY Stands Template and Calculator - Reef Central Online Community

DIY Stands Template and Calculator Do It Yourself

www.reefcentral.com

It’s all in here.

 

[RocketEngineer]

Oh, and I used a max deflection as my limit, not the failure point of the lumber.

 

[Ben Pedersen]

Thank you. I read through the posts. Looks like using 4x4 in the corners is very similar to the design in the posts except you use 2 2x4s.

Still considering using 4x6s to span the distance. Just wondering if the sag would cause any issues. I know using 2x8s would help. At the same time, using a surface on top of the spans would also provide additional rigidness.

I read that your max deflection is 1/8" is that correct?

 

[billwill]

Can you provide the math and supporting information that aided you in arriving at that conclusion.

Hah, for a consulting fee!

 

[Pistondog]

It seems to be complicated math but maybe not. I think you would have to use calculus. And it has been 20 years since I did any of that.

It is easy to calculate load but less easy to calculate distribution of load as the load is not exactly over end supports. As the load gets further from the end support, I would guess there is a exponential drop off of load bearing strength until you pass the middle and it starts to increase again.

That is why I was thinking to use 4" x 6" with the 6" vertically supporting the load. The math that I don't know is how to calculate the span load bearing capability of a 4" x 6" with end support (4" x 4"), and the load distributed starting 6" from both sides. If I knew that, I could multiply it by as many 4" x 6" necessary to support the tanks weight.

But then there is the question regarding rigidity.. Would the support bow enough to cause the tank to deform and stress?

A ton of water.
Why not metal to keep things leaner than wood?
Like 80/20 from grainger, we used to use that for machine tool bases, heavy.
Isn't that what the big boys use?
More money, but probably less than a scoly master.

 

[billwill]

Thank you. I read through the posts. Looks like using 4x4 in the corners is very similar to the design in the posts except you use 2 2x4s.

Still considering using 4x6s to span the distance. Just wondering if the sag would cause any issues. I know using 2x8s would help. At the same time, using a surface on top of the spans would also provide additional rigidness.

I read that your max deflection is 1/8" is that correct?

Strongly recommend the concept of using two pieces of thinner lumber with glue and screws to make our larger pieces. There is a reason glulam beams are significantly stronger and lighter than traditional lumber. You can look up the properties of all these wood profiles to determine your deflection too btw. Google beamboy for a free program to calculate the deflection after you look up the moment of inertia (moi) to plug into the program. And deflection is but one piece of the puzzle; buckling and racking are the other much more dangerous ones to worry about. Again, follow rocketengineers advice on pockethole screw attachment for all of this too so this doesn’t collapse on itself.

 

[Ben Pedersen]

Strongly recommend the concept of using two pieces of thinner lumber with glue and screws to make our larger pieces. There is a reason glulam beams are significantly stronger and lighter than traditional lumber. You can look up the properties of all these wood profiles to determine your deflection too btw. Google beamboy for a free program to calculate the deflection after you look up the moment of inertia (moi) to plug into the program. And deflection is but one piece of the puzzle; buckling and racking are the other much more dangerous ones to worry about. Again, follow rocketengineers advice on pockethole screw attachment for all of this too so this doesn’t collapse on itself.

I will look into Beamboy. Do you know if the calculator can take into consideration that the load starts 6" from the ends?