700 gallon fish tank project!

Hey, new to all this so just getting the hang of it. Currently finalising plans for a 12ft display tank. Going to be 2ft steel cubes (drawing included) with plywood tank. Any experience/advise would be much welcome! I'll lay out what Iv thought through so far and correct me if I'm wrong or could improve anything. Each 2ft steel frame will need to hold 750kg to be safe and will all be bolted together once in place. I'm thinking 2x2" steel box section will be adequate with the design to support that weight. Will be putting 4x2 stud framework around the wall and they double skin of 16mm ply wood. Iv heard good reviews of pond armour paint so opting for that instead of full fibreglass the tank. 11ftx2ft 12mm glass panel with a 2" lip to bond too. Opted for a 600L fluidised sump running K1 media and a 25,000lph pump. Will have side overflow with 3 40mm drain pipe feeding the pump with optional cut off valves is all 3 drain too fast. 24/7 drip feed into the main tank with overflow drain in sump to drain excess water. Any recommendations/changes options is great fully appreciated. Only been keeping discus since September and due an upgrade from a 100gallon tank

your frame you are stating its max load of 750kg but you will have 2600kg(700 gallons) of just water not including the weight of the glass which would be over 200kg easily, you are basically going to have 3 metric tonne of weight when all is said and done. looking forward to following your progress.

Yep. Agree Departure. Your going to fall short by your math in regards to support. Can you do thinner but more Stella frames? Also, whatever you do, definitely strive to go well over the support you need rather than meeting the weight. Excited to see your build.

Yea, I definitely want to see what comes of this. Please keep us all posted.

You want to build to support twice as much as you plan on putting on the frame to be on the safe side. I would definitely go with steel for a tank this size.

Hi,
You state 2ft Square cubes, but your sketch differs.
What is the floor composition in the room?
Bolting box sections together isn't a very good connection using circa 5" bolts through thin walled sections.
Would it be possible to weld the cubes together in-situ? if so then continuous top beams would be preferred.

phwew... and I thought keeping my 180gal clean was a lot of work - can't imagine maintenance on a 700gal :p Looking forward to seeing your progress - like everyone said though, plan on a stand that will hold double the weight you're putting on it - would be a shame (and a mess) to have the frame give out spilling that huge tank onto the floor.

If you look at his drawings, he is planning on using six of these frames that have a max load of 750kg a piece... That's a total maxload of 4500kg. Not quite double, but probably north of 150% of what he needs to support the glass, plywood, water.

Would it not make sense to construction a stand without joining 6 sections together. A load is best supported by a continuous solid unbroken section know as a beam/lentle or rafter that can have support post between span.
Is there a reason for the cubed sections that I am missing.
Where is my friend Skip the Eng. when you need him...

...Ralph

You may want to pour a concrete bed to put the stand on, to ensure level and flat for starters. Also, I would incorporate some diagonal bracing both front to back and side to side to reduce shear issues. I know welds are strong, but...

also consider your floor with all that weight. Depending on where the tank will be (do not suggest anywhere else than ground level) - you'll might have to enforce the weight bearing beams. I had to go into my crawlspace and add some floor support just for my 200g. Tank weight is one thing, but tank weight with people walking in-front, looking at fish and dynamics of vibration created is another thing to consider. Looks like an awesome project. Good luck!

edit: "dynamic load" was the term I was looking for :-)