Large tank learning curve

Discussion in 'General Discussions' started by fux940510, Aug 12, 2019.

  1. fux940510

    fux940510

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    Hi everyone

    I picked up a 150cm long, 45cm wide and 55cm high tank a few months ago. Center brace was broken and seams were starting to flake off, but otherwise looked fine. I got a new brace to replace the broken one, new lids, resealed etc.

    Tank was sitting under my carport, as it was the best place to work on it. I slowly filled it up on Tuesday after waiting 48 hours for silicone to cure. Tank looked good, no leaks, happy days. I was planning on leaving it for a week just to make sure everything was holding.

    Come Saturday afternoon, after a cold and lazy morning not leaving the house, i walk outside to an empty aquarium and shards of glass everywhere. The brace had popped loose on 1 side (my mistake, thought i had it in place properly), and disaster ensued unnoticed. On closer inspection both of the lengthwise braces had cracks, as well as the base. The whole thing is pretty much unusable now. One thing i noticed when pulling out the broken pieces of glass is that I was still getting that vile silicone smell - maybe i didn't leave it to cure for long enough? There was bracing along the long sides at top and bottom of the glass, as well as the replaced center brace across the middle.

    Out of curiousity, i plugged the dimensions into one of the online calculators (150cm x 45cm x 55cm with 6mm glass), and turns out the safety factor is/was exactly 1. No good. I'm just glad i did this test outside, having 350 litres of water running through my house wouldn't have been fun.
     
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  3. BoelderBeestie

    BoelderBeestie

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    Use no less than 8mm, always. You have to stay below 40cm height with 6mm. Think about it this way, you can have 1 square kilometer tank made with 1mm glass if its only 1cm high, the more height, the more pressure.
     
  4. OP
    fux940510

    fux940510

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    Yup, all makes sense :) my (admittedly occasionally faulty) logic says the length will have an affect too - assuming equal material strength and thickness, a longer piece will have more deflection. Maybe i'm wrong and don't have all the right data and knowledge, but i'm happy to be proven wrong.

    Seeing as the big tank bug has bitten, i'm thinking about either a custom-made tank from one of the local guys or doing it myself - I'll need to do some more research on how bracing affects safety factors, and come up with a design that will be easy to use and also strong.
     
  5. BoelderBeestie

    BoelderBeestie

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    Nope, otherwise you would get the bends every time you put your head a few cm underwater in the ocean.
     
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  6. Niel

    Niel

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    Hi Guys,

    read that with interest, I am in the process of planning for a set-up off a 10ft tropical planted tank.... any1 know of any suppliers or tank builders in the Durban area .

    would appreciate any lead or advice regards
     
  7. OP
    fux940510

    fux940510

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    Wouldn't that be due to your head being a misshapen sphere, and sphere's being the best at containing/resisting pressure?

    If i take a plank 10cm wide and 100cm long, vs a plank 10cm wide and 20cm long and place a 40kg weight on each, wouldn't the 100cm plank bend more?
     
    Last edited: Aug 12, 2019
  8. BoelderBeestie

    BoelderBeestie

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    The plank theory is correct but remember gravity pushes, yes pushes you towards the center of the earth because of the earth's mass bending space time. Meaning that pressure increases the more water you have above you not how much water you have parallel to you.
     
  9. OP
    fux940510

    fux940510

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    That makes sense, but say you have 1 aquarium that is the above 150x45x55, and other tank that is 82.158 x 82.158 x 55. Both tanks hold 370 litres, both have a height of 55cm. Why would the panel that is 150cm not bend more than one that is 82.158? It is still having to contain the same amount of water, same height so the same pressure, but a shorter length should mean less movement.

    ps: Not trying to pick apart the theory, just trying to understand it :)
     
  10. BoelderBeestie

    BoelderBeestie

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    The shorter panel will flex less.
     
  11. BoelderBeestie

    BoelderBeestie

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    So if you can see any flex on one of your tanks' side panels.
     
  12. BoelderBeestie

    BoelderBeestie

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    Ok think about it this way. You have a vertical 20cm radius pipe the holds 5000 liters of water you put one tap just below the water surface and on at the bottom. Which tap would you put your mouth over to drink water from? Top one, or bottom one?
     
  13. OP
    fux940510

    fux940510

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    I understand that more height means more pressure, which requires thicker glass to withstand.

    Therein lies the rub. If it flexes less, wouldn't you be able to use a thinner panel?
     
  14. BoelderBeestie

    BoelderBeestie

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    Yes you will be able too.
     
  15. OP
    fux940510

    fux940510

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    Thanks for the confirmation, and apologies for dragging this out so far :)
     
  16. BoelderBeestie

    BoelderBeestie

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    Nah I'm a trekkie so I enjoy techno babble:thumbup:
     
  17. A new day

    A new day

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    10 foot tank - wowzers! Can’t offer any advise but sure would like to see it! :thumbup:
     
  18. BoelderBeestie

    BoelderBeestie

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    That's going to be a monster, joh.
     

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