Will this tank stand be strong enough

[David Crabb]

Hi all, I am designing a stand for a 505 US gal (1911 lit) tank I am getting made for me. I have made up a design in sketchup and just wanted some advice on wether it will be strong enough or not.

The tank is 9' x 3' x 2.5' (274cm x 91cm x 76cm)
The tank including water will weigh 5406 lb (2452kg)

The stand is made from 4' x 2' pine apart from three cross struts at the top which are made from 4' x 4' pine.

I have put some pictures (along with a sketchup file) on my website:
http://www.davidcrabb.co.cc/tank
The design isn't complete but the main structural design is done. The stand will be enclosed but only by doors as this tank will be free standing in the middle of a room.

My question is wether or not the stand will take the weight of the tank. Any advice/comments/suggetions greatly appreciated.

Regards
David

[David Crabb]

Some more tank information:

Tank volume:
67.5 Cubit feet
1911 litres
420 gallons(uk)
505 gallons(us)

Tank weight:
9' * 3' * 2.5'
274cm * 91cm * 76cm
area (cm squared):
Front/back 41648
sides 13832
bottom 24934
Total 80414
cm Cubed: 204251
weight:
541265 grams
541 kg
1193 lb

water weight
1911 kg
4213 lb

Total weight:
2452 kg
5406 lb

[Matt Meiser]

I wouldn't even think of it without significant diagonal bracing.

How is the floor this is going on constructed? Can it take the load both overall and at the point where the feet contact the floor? Assuming the lumber is standard construction lumber, the feet will exert 170-something PSI on the floor.

[Stephen Musial]

Short answer - No.

You want to do this either more along the lines of framing a wall - 2x4 studs every 16" with a double top and bottom plate or make it all out of stainless steel.

What kind of tank - reef, saltwater fish only, African or South American cichlids?
Will it have a sump?
What kind of filtration?
Lights, ballasts, etc?

As Matt said, is this on a concrete slab or a joist floor?

[Dennis Thornton]

Virtually any tank stand should use plywood for the back and sides at the very least. Think about it. That tank will weigh more than a typical car and just about that of a full size truck. Would you be safe in that stand with a F150 on top? :eek:

[Ben Hatcher]

David,
Using plywood on one side or just beefing up the upper and lower stretchers with 2x6 stock should be sufficient to prevent raking. Glue and bolt it.

If the aquarium is glass, you'll want to make sure that the upper portion is rigid to prevent stress cracks. The beefier upper stretcher will help here, too. You may consider notching the upper portion of the legs such that the stretchers sit directly on the notch. This will transfer the load through the legs directly, instead of having to go through the fasteners to the legs.

My concern is the floor. If you're on a slab, you're golden. If you're putting this in the middle of a room supported by span of joists, you're looking for some serious saggage.

[David Crabb]

Thanks for all your replys.

It will be going on a concrete floor so thats no problem and the tank itself is being being constructed by a glass fabricator who specialises in tanks, so I know the tank itself will be fine.


You may consider notching the upper portion of the legs such that the stretchers sit directly on the notch. This will transfer the load through the legs directly, instead of having to go through the fasteners to the legs.




You want to do this either more along the lines of framing a wall - 2x4 studs every 16" with a double top and bottom plate


Both very good ideas I think I'll go back to the drawing board and redesign. However, plywood on the back isn't really an option, the front and back is going to have decorative oak panel doors, but I could still use plywood on the ends as these don't need to be doors and can be covered with oak paneling.

It's going to be a Marine reef tank, I'm putting a refugeum underneath along with a fluval FX5 pump and filter. Fish wise I'm thinking clown fish, maybe a couple of seahorses or a couple of the less aggresive reef safe puffer fish along with an assortment of others that will (hopefully) get along and not kill each other.

I will post a new stand design when Its done for more criticism :)

Many thanks
David

[Tom Sontag]

I see two problems, one already hinted at. Supporting the weight is one issue, but supporting it without flex which would cause a leak or worse is another. I would design the top of the stand first, as a completely rigid element. Torsion box perhaps, or a slab of concrete. Six verticle two bys can support a lot of weight technically speaking, but the cross bracing issue would also be a key. Side to side movement is no good either.

The other issue is aesthetic. I presume such a tank will be a major focal point. Why not make the stand deserving of all those eyes? Store bought 2x4s will always look like rough carpentry. This is a major downfall IMO of many otherwise awesome tank setups. I do not see why standing in the middle of the room mean the cabinet cannot have doors to hide all the inevitable stuff that goes below. Build it with hardwoods and make it look like the piece of furniture it deserves to be.

It is going to be worth it.

[Cliff Rohrabacher]

No. For dead weight such a structure might be able to carry it but, in the real world nothing is ever perfectly static.
There'll be side loads, torsion of wood movement, and the occasional bump from some one walking by or working on the aquarium.
That tank will - I guarantee you - end up on the floor.

[Phil Thien]

I will also add that, if the top of the stand is the same size as the aquarium bottom, you should avoid edging the top of the stand with anything approaching the width of the aquarium's bottom frame.

Otherwise, the weight of the aquarium is resting entirely on edging that is attached to the plywood (with maybe biscuits and glue).

What I've seen happen is that the edging joint fails, then the aquarium drops the distance between the bottom of the bottom glass, and the bottom of the frame. You'd be amazed at how quickly that can turn into a disaster.

[Stephen Musial]

You never did say what your floor was but it probably won't be a problem - just think of it as a big waterbed.

Is it going to be a glass tank or acrylic? Consult with the manufacturer - some want only perimeter support, others want full bottom support. In either case, a double layer of 3/4" plywood will suffice. Also see if they want padding between the tank and stand or not.

Bag the idea of having a reef and sea horses - sea horses need almost no flow while corals need a lot. Don't forget to take into account the holes in the bottom of the tank for drainage and supply - you don't want those lining up over your tank supports. Also, don't forget about ventilation and heat dissipation for under the tank - you don't want the 'fuge to overheat. Since this will be in the middle of the room, you're not going to have the luxury of hiding pipes behind the back of the tank or in a wall so you might think about a Tunze wave box.

I'd consult with a local reef club first and get the tank mechanics figured out first then worry about the stand after that.

p.s. Mr Sontag - when's the next weekend you're going to be open for retail and when are you going to move your operation to Webster Groves - there are a couple of big empty buildings by the railroad tracks you could probably get for a song. :)

[Adam Cavaliere]

Not that this isn't a GREAT resource, but I also would consider a fish forum too. I participate once and a while on cichlid-forum.com. While it isn't the type of tank you are building (cichlid), the guys on there have built some pretty large tanks and have much experience with the design of supporting such large tanks. I am not trying to discourage posting here, but maybe cross posting to another site with fish expertise too!

[Ryan Cassidy]

For a 500 gallon tank I would beef up the leg supports and upper frame. In addition, I would also run a center support along the bottom for your sump/refugium/calc reactor/skimmer/pumps etc. It will be hidden and the extra strength (while probably not needed) is cheap insurance. As well, if you used 3/4 ply for the sides and to cover the face (a frame of some sorts, but all one peice) that would definitely help with overall rigidity. The back I would recommend making a 6-8" frame of plywood. It won't inhibit what you are doing in the back, but will help sturdy it some.

One of the biggest issues you will have with that tank is deflection due to its length and width. If it's all acrylic the bottom will be flat against whatever you cover the top with, if it's glass and is "framed" you'll want to put a piece of 3/4 ply in there to keep the the bottom from deflecting too much.

A couple of reccomendations from someone who has been there done that with reef tanks as well:

Allow of plenty of forced ventilation. Fans etc in the sump area.
Make the sump area water tight. Caulk and use a marine grade paint. You will spill water. :-)
Line the sump area with Neoprene. It will eliminate most if not all vibrations and make for a really quiet setup.

Hope this helps.

Cheers,
Ryan

[Rod Sheridan]

Come on guys he's making it out of 2' X 4' pine, that should hold up more than the concrete slab will:D

regards, Rod.

[Christopher Zona]

Might I suggest a combination of a welded structural steel frame with wood facing?

The suggestion of the rigid base in combination with the welded frame will offer much more to the strength of the frame. Then you can give whatever cosmetic appearance you desire with the wood.

Just a thought.

[Mike Cruz]

Since you are insisting on cabinet doors underneath, maybe the cabinet doors could be on the ends spanning the lower 3/4 (vertically) of the base so the top 1/4 could be plywood/bracing, with eight verticals instead of 6, therefore giving you area on the front and back to put both doors (middle compartment) and plywood/bracing (2 end compartments).

[David Keller NC]

David - you've already gotten lots of suggestions on the structure. I've a couple of other comments. What sort of pine you use will sensitively affect the sturdiness of the final design. There is a huge difference between the strength of eastern white pine, so-called "SPF" (spruce-pine-fir) and hard yellow pine (usually sold as SYP - southern yellow pine). SYP is probably strong enough, as is true douglas fir. White pine, so-called "white-wood" and SPF is not.

Another comment - you don't say too much about the refugarium. I'm assuming this is not your first coral reef tank, and you may already know this, but you absolutely must use an over-flow design down to a sump that processes the water and returns it to the tank for a coral reef tank. Without the skimming action of overflows across the top surface of the tank, it will quickly turn from a coral reef into a swamp.

One other consideration is that your tank will weigh more - considerably more - than the calculation of water weight and tank weight would indicate. Generally speaking, one goes with about 2 lbs. - 4 lbs. per gallon of live rock in a reef tank. Some of that weight will be subtracted because it displaces water, but all rock, no matter how high-quality (the higher the quality, the less dense), will exceed a specific gravity of 1.0.

The type of rock will sensitively affect this calculation. Tonga or Fiji rock is typically the least dense. Harvested terrestrial rock from the Atlantic is far more so.

One other design comment - realize that you're going to absolutely require a chiller. The surface area to volume ratio of a tank like this is far too low to rely on unforced convection/condution. Most hobbyists include the chiller inside the bottom of the stand, with the air-flow from the outside through the evaporation coils back to the outside again accomodated by ducting that's built into the stand.

[Scott Gibbons]

My tank was of similar proportions, i had a company weld me an aluminum stand out of 2x2x.25 wall. i think i paid about $600.00. I fully understand the amount of money you will be spending and $600.00 is a drop in the bucket...I guess I am making the assumption you are doing a reef.