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Calculating media required for growbeds
http://byap.backyardmagazines.com/forum/viewtopic.php?f=8&t=26434		 Page 1 of 5
Author:  SydneyChick [ Dec 22nd, '15, 18:55 ]
Post subject:  Calculating media required for growbeds
Ok - so an online calculator I used tells me I need 1 tonne of Scoria for each grow bed. (1m X 1.2m and 45cm deep)

That seems very excessive! Especially at a cost of $200 per tonne from my local supplier.

So my question is - what is the best way to calculate how much scoria I need?

Thanks in advance!
Author:  Yavimaya [ Dec 22nd, '15, 19:06 ]
Post subject:  Re: Calculating media required for growbeds
scoria is measured in cubic metres, it is very light an a tonne would be more than your roughly one cubic metre.

find another supplier, i dont know what costs are like up there, but in vic it is around $65/m.

Your calcs would put you at needing about 1/2 cubic metre.
Author:  SydneyChick [ Dec 23rd, '15, 05:48 ]
Post subject:  Re: Calculating media required for growbeds
Yavimaya wrote:
scoria is measured in cubic metres, it is very light an a tonne would be more than your roughly one cubic metre.

find another supplier, i dont know what costs are like up there, but in vic it is around $65/m.

Your calcs would put you at needing about 1/2 cubic metre.


Thanks Yavimaya! At least your calculations have halved my costs.

The cheapest I can find it with an Internet search is $180 per cubic metre. The joys of living in Sydney!
Author:  SydneyChick [ Jan 29th, '16, 11:21 ]
Post subject:  Re: Calculating media required for growbeds
I just called BCSands.

They're the cheapest so far and we deliver me 2.3 cubic meters for $530

ANL were quoting me 3 cubic meters for $640

Considering I only need 2 cubic meters I know who I'll be going with
Author:  SydneyChick [ Jan 29th, '16, 11:27 ]
Post subject:  Re: Calculating media required for growbeds
Haha - spoke too soon. Turtle Nursery just quoted me $499.50 for 2.3 cubic meters of 14mL scoria
Author:  Max47 [ Jan 29th, '16, 11:46 ]
Post subject:  Re: Calculating media required for growbeds
Make sure you test your media in vinegar. If you see a chemical reaction its not suitable for aquaponics.
Author:  Gunagulla [ Jan 29th, '16, 12:20 ]
Post subject:  Re: Calculating media required for growbeds
Why use scoria when river gravel works very well, at a lot less cost?
1300kg/m^3, and $65/m^3 here
Author:  SydneyChick [ Jan 29th, '16, 14:59 ]
Post subject:  Re: Calculating media required for growbeds
Getting better and better Martins Building a landscape supplies just quoted me $459 for 2.5 cubic meters incl delivery.... :cheers:
Author:  SydneyChick [ Jan 29th, '16, 15:02 ]
Post subject:  Re: Calculating media required for growbeds
Gunagulla wrote:
Why use scoria when river gravel works very well, at a lot less cost?
1300kg/m^3, and $65/m^3 here


Because scoria is only 1000kg per cubic meter and given this is my first ever AP build I want something as light as possible without totally breaking the bank
Author:  SydneyChick [ Jan 29th, '16, 15:03 ]
Post subject:  Re: Calculating media required for growbeds
Max47 wrote:
Make sure you test your media in vinegar. If you see a chemical reaction its not suitable for aquaponics.



Oh really!?! What does the vinegar test expose?
Author:  dasboot [ Jan 29th, '16, 15:17 ]
Post subject:  Re: Calculating media required for growbeds
SydneyChick wrote:
Max47 wrote:
Make sure you test your media in vinegar. If you see a chemical reaction its not suitable for aquaponics.



Oh really!?! What does the vinegar test expose?


Limestone,shouldn't be a problem with scoria.,but it doesn't hurt to test.
Author:  Stuart Chignell [ Jan 29th, '16, 17:28 ]
Post subject:  Re: Calculating media required for growbeds
So the calculator told you needed 2 m3 rather than the 2t you were originally talking about?

How big is your fish tank?
Author:  Stuart Chignell [ Jan 29th, '16, 17:32 ]
Post subject:  Re: Calculating media required for growbeds
And Im guessing you have 4 GBs?
Author:  rendang [ Jan 29th, '16, 20:29 ]
Post subject:  Re: Calculating media required for growbeds
Quote:
Gunagulla wrote:
Why use scoria when river gravel works very well, at a lot less cost?
1300kg/m^3, and $65/m^3 here


Scoria has far and away more surface area than gravel so wouldn't you get more bang for your buck from each growbed ?

I think its mined in Victoria so that's why its cheaper there. It doesn't contain limestone, so there's no need to test for it.

It helps if you have a groundsheet or tarpaulin for them to dump it on, just saves having to pick it out of the lawn. I've used 14mm and 20mm in different systems, others have used 10mm, I think the 14mm is a bit easier to work with than the 20mm.

Congratulations ! Your almost there ! :cheers:
Author:  Max47 [ Jan 29th, '16, 23:32 ]
Post subject:  Re: Calculating media required for growbeds
I used scoria(red lava rock) in my grow beds. It had a lot of red dust with it and had to be rinsed before being placed in the grow beds. I would also suggest you keep a little extra, I had a few 5 gallon buckets set aside. After my system operated for awhile the media settled and I had to add a little more.
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