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grow bed strength/grow bed stand
http://byap.backyardmagazines.com/forum/viewtopic.php?f=8&t=22495
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Author:  katali [ Jul 28th, '14, 20:11 ]
Post subject:  grow bed strength/grow bed stand

I'm hoping someone can help me with some numbers, I need to get or make staging for the centre isle of my hope-for polytunnel, but I'm not sure how much weight it needs to hold. My expected grow beds will likely be 130l dog bath type, is anyone able to give me a rough figure for how much that might weigh when full of cheap heavy gravel in a constant flood setup? I'm pretty sure the measurements were 4' × 2' × 1' if that helps. Thanks for any help!

Author:  Ian [ Aug 2nd, '14, 19:44 ]
Post subject:  Re: grow bed strength/grow bed stand

Water = 1 Kg / Litre
Gravel = (about) 1800 Kg/Litre

Do the math.

Author:  skeggley [ Aug 3rd, '14, 08:32 ]
Post subject:  Re: grow bed strength/grow bed stand

Ian wrote:
Water = 1 Kg / Litre
Gravel = (about) 1800 Kg/Litre

Do the math.


:shock:
Damn that's some heavy gravel! Wouldn't wanna be washing that...

Author:  Gunagulla [ Aug 3rd, '14, 08:44 ]
Post subject:  Re: grow bed strength/grow bed stand

Yea, way heavier than my washed 14-20mm river gravel, which is 1300kg/m^3

Author:  katali [ Aug 3rd, '14, 16:33 ]
Post subject:  Re: grow bed strength/grow bed stand

I was thinking that sounded very heavy!

Author:  Blizzard [ Aug 3rd, '14, 17:48 ]
Post subject:  Re: grow bed strength/grow bed stand

katali wrote:
I'm hoping someone can help me with some numbers, I need to get or make staging for the centre isle of my hope-for polytunnel, but I'm not sure how much weight it needs to hold. My expected grow beds will likely be 130l dog bath type, is anyone able to give me a rough figure for how much that might weigh when full of cheap heavy gravel in a constant flood setup? I'm pretty sure the measurements were 4' × 2' × 1' if that helps. Thanks for any help!



I an using 90mm/by 35mm treated pine, 2400/970/600mm high, but I am using 500ltr of the clay media which is around 150kg, plus around 120ltr of water at 120kg, if you went for steel I would suggest 76mm/38mm,1.2mm thick box tubing, or patio tubing,
I am not sure if this helps, but you could always screw two pieces off 90mm/35mm together giving you better centre strength, offcourse you could share the load with two cross beams as I have done, at 800mm apart approximately, but in your case maybe less distance,
If I knew how to show a video that didn’t max out everyone’s wifi I would put it up,

I hope this will give you some idea as to what you can do,
:think:

Author:  Ian [ Aug 5th, '14, 11:48 ]
Post subject:  Re: grow bed strength/grow bed stand

skeggley wrote:
Ian wrote:
Water = 1 Kg / Litre
Gravel = (about) 1800 Kg/Litre

Do the math.


:shock:
Damn that's some heavy gravel! Wouldn't wanna be washing that...


Here in Queensland, we live on the largest Blue Rock or Basalt, deposit in the state. Solid Basalt has a mass of around 3000Kg/cu. m., Broken Basalt around 2000Kg and the crushed Basalt (about 15 to 20mm pieces) is 1850Kg/cu. m. The latter is what we have to 3/4 fill our grow beds with a topping layer of Canna Clay Balls. I'm sorry I mistakenly put the mass /LITRE not /Cubic metre :? posting.php?mode=quote&f=8&p=468449#
Anyway, I wash it in my cement mixer with a steady supply of water and have never had any trouble doing it this way.

Cheers IanK

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