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Support for 300 Gallon tank


Iridan

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Hello folks.

 

We are getting back into salt water after a several year break.  After a lot of discusion we have decided on a 300 gallon tank.  As the basement is the reason we never got back into our 150, because it is not where people are, we want to put the tank on the main floor.  From what we are looking at we will be doing the plumbing down into the basement and plumbing it back up to keep th volume down a bit.  This means that we are looking at a bit under two tons of weight up on the floor.  Facts about the floor:

 

16 inch offset on the joists

2 X 10 joists resting upon the main structural support beam.

No finished ceiling in basement.

The tank we are looking at would have a 6 foot by three foot footprint and would be up agianst the main loadbearing wall.

 

I have been looking at adding a pair of jack posts supporting a length of 2 x 10 that would be running perpendicular to the joists just outside of the footprint of the tank.

 

Thoughts and suggestions?

 

Thank you

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I would definently consult a structural engineer for a load this size. Then you will know what and where to put the extra support.

 

But sounds like a great tank build!

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I would definently consult a structural engineer for a load this size. Then you will know what and where to put the extra support.

 

But sounds like a great tank build!

Sound advice!

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The tank we are looking at would have a 6 foot by three foot footprint and would be up agianst the main loadbearing wall....

 

I have been looking at adding a pair of jack posts supporting a length of 2 x 10 that would be running perpendicular to the joists just outside of the footprint of the tank.

 

This is definitely an acceptable approach. What you may want to do, though, is to laminate two or three 2x10's together to form a heavy beam. I'm not entirely clear if the concrete below can handle the constant load over the baseplates of two jack posts. Your 2 ton estimate puts about 1 ton on each post or about 125 pounds per square inch. That doesn't seem like much and it sounds like it shouldn't be a problem. You can always spread the load across more of the floor if needed. A good person to run this by is DaveW - he's here on the forum and has been in construction all of his life.

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Just for perspective, for my 8' long 350g the engineer called for 2 triple-layered 9.25" LVLs.  YMMV. 

 

The floor construction is 2x10 joists at 16" spacing.  Joist span is 15', supported on one side by the concrete wall foundation, and a steel beam on the other side.  Tank footprint is parallel to the joists and LVLs.

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Jon, I'm not sure what you mean by the 2 triple-layered 9.25"lvls.  But I am interested in more details.

Origami, I would hapily talk to DaveW. 

 

Thank you all for the suggestions!

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LVL is laminated veneer lumber.  It comes in dimensions roughly similar to 2x10s and 2x12s. Because LVLs are manufactured, they don't have inconsistencies like knots or warping, and are stronger. 

 

In my case, the engineer took three LVLs that were 9.25" x 1.75" x 16', and bolted them all side by side to create a heavy duty 16' beam.  He made two beams like this, using a total of 6 LVLs.  One runs under the front of the tank, and the other runs under the rear.  As I recall his explanation, he said lots of support was required because of the long distance the joists spanned.  The floor was extremely bouncy before they did this (and other!) work to reinforce the floor. 

 

I used a 4000lb load for calculations (water, glass tank, steel frame, wood stand, wood canopy, equipment and supplies in stand, then rounded up).

 

I would never recommend you use this is as blueprint for your build.  I just gave this as an example of what was required in my case.

 

Posts are also a valid option.  The engineer mentioned this, but I didn't want them in the finished basement.  A previous general contractor mentioned that we might need to dig and pour a concrete footing under the post(s), depending on the engineer's calculations.

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Go LVL or PSL (Parallel Strand Lumber). I went with PSL's since you can get them pressure treated (our tank areas sometimes get wet...right?) for my stand, even though this is to reenforce the floor. They are the strongest and stiffest engineered-lumber beams. it also allowed me to have just corner posts (6" x 6") on an 8' long 48" wide stand for a 300g tank. Pics in my build.

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its not a big deal i just made a stand for a 300 and a 350 all on my posts a double 2x8 will be more then enough and lolys will be fine but 4" x 4" allso fine its just not a big deal 2 or 3 thousand pounds aint much , ive built about 10  or 20 million dollars worth of houses in fairfax dezigned most of them did some insane enginering lot more wieght then that 

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Iridan,

 

If you have 2x10's on 16" centers, it will be very easy to strengthen your floor.  You don't need to beef it up, but doing so will probably save you some cold sweats in the middle of the night because people are always afraid of what they don't understand.  

 

The simplest method would be to hammer more 2x10's of the same length right next to the originals.  Better still if you could brush a good layer of Elmer's wood glue where the two wood surfaces will touch, and the top of the new 2x10 where it will touch the plywood floor.  Even more better if you can jack up the floor and put a slight camber in it before nailing the dimensional beams together.  Then put in enough nails to hold everything in place for two days until you let the jack down and move 16" to the next joist/beam.  The nails only serve to hold the wood in place until the glue dries, the glue and wood have all the strength.

 

What I mean is that you should glue the new 2x10, give it 20 minutes to develop a skin so it won't drip into your nice haircut, then hammer it into place beside the old 2x10.  Then put one 16 penny nail into the center of the bearing distance.  By that I mean if the 2x10's span 10', then you'll put a single nail in at the 5' mark.  Then take a hydraulic car jack and jack up the two beams about an inch.  Don't worry, when the glue cures and you remove the jack and post in a couple days, the beam will drop halfway down to only half an inch and will not be noticeable from the floor above.

 

Now you will have an upward curve called a camber in your floor.  When you drive down the highway and see an empty 18 wheeler, you'll notice the steel has a very large camber, as much as 6".  When a cambered beam is put under a load it is much stronger than a straight beam which begins to sag under a long term load.  If you REALLY want a strong floor, glue a 2x6 flat against the bottom chord of the two beams, also while the camber is made by the jack.  To keep the glued 2x6 from sliding, nail it in place after the camber has been put in.

 

I hope you understand the terms used here, if not I can translate them into more plain english.  I have been around Walt's house building for 20 years and you can believe him that your standard floor is already fine to hold 2500 pounds.  Your room is probably 200-300 square feet so you are only adding 10 pounds per square foot to a floor that is rated for 4 times that stress.  

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