Calculating media required for growbeds

SydneyChick

Gunagulla wrote:

hmm, IBCs out in the sun... do you know their age and history?

They will be fine for a number of years if they haven't had much sun/UV exposure, but I would be a bit concerned about the IBCs going brittle over time when loaded up. Best to paint or cover them to protect them from UV and prevent that happening if you want to keep the system going in the long term.

How well do the frames support the bases of the IBCs, ie no bent bars etc? I'd say they will probably be fine, but another option worth looking at is what I did with my first system- a mix of expanded clay and gravel, keeps the weight down without being too expensive.

Is that supporting pipe regular galvanised water pipe - ie quite thick walled & heavy?

Yav, yes I know its fine to work with, as is river gravel, but I know someone who complains about the roughness on their fingers

The whole system is in the process of being clad so once the gravel goes in there should be very little of the IBC bladders that see daylight.

I tried to pick the best cages so straight bars and new not rusty.

The supporting pipe is galvanised steel fencing - not water pipe.

WhenI cut it the walls were pretty thick... About 0.5-0.6cm

SydneyChick

I'm just not confident my support frame can handle the extra weight of the gravel so I have ordered the scoria.

It's being delivered tomorrow! :headbang:

Yavimaya

if you end up wanting to wash that scoria, dont be a fool like most people and try to hose the pile down or scatter it out and try to pressure wash it, both are just a disasterous waste of time and water.

fill one of your bed totally full of water, half fill with scoria, using a garden sieve scoop and give a quick rinse a sieve full of rocks, then dump into your proper bed, untill you get to the last bed. i think you will find there are many centimetres worth of very fine (and very hard once settled) dust.

SydneyChick

Yavimaya wrote:

if you end up wanting to wash that scoria, dont be a fool like most people and try to hose the pile down or scatter it out and try to pressure wash it, both are just a disasterous waste of time and water.

fill one of your bed totally full of water, half fill with scoria, using a garden sieve scoop and give a quick rinse a sieve full of rocks, then dump into your proper bed, untill you get to the last bed. i think you will find there are many centimetres worth of very fine (and very hard once settled) dust.

Thanks Yavimaya! I was planning on filling a wheelbarrow with the scoria, tilting the wheelbarrow by resting the back rests on a wood sleeper (So that water runs out of the barrow) and gently hosing the barrow full of scoria until the water runs clear.

Is this not a good idea?

I'm confused with your plan. - do you mean that you fill a grow bed with water than rinse the scoria outside the grow bed and only put it in once it's clean?

Or do you immediately half fill the grow bed with unrinsed scoria?

Yavimaya

your idea wont work well because scoria dust is quite heavy for its size, like sand it wont get washed away easily.

my way of doing it is to fill a growbed (or spare ibc, etc) with water, then dump dirty scoria in, use a sieve to pick it out (scoop with sieve and fill it) then shake up and down once or twice in the water to "wash" better, then dump that straight into the bed where it is to go.

Max47

I washed my scoria using a couple old plastic buckets. I drilled several holes in the bottom, ran a hose in the bucket and twisted the bucket back and forth to agitate the rocks until the water ran clear. It took some time and a little extra labor but there was a lot of red dust. That red dust almost turns into cement when it dried, I am glad its not in my system.

Gunagulla

I've done all my river gravel with the tipped wheelbarrow, and it works pretty well. Anything too heavy to wash out wont generally be a problem in the system, as it wont move very far.
I almost fill the barrow with gravel, then fill with water, tip it up the normal way to drain water, then spray it down hard (but not hard enough to wash out the gravel) to remove more sand and fines, then I wheel it to the GB and tip it in.

Yavimaya

it may not move very far, but people have a go at Bui and his anaerobic zeolite, what is the difference between purposely doing what he is doing and purposely not washing scoria, considering we all know that there is A LOT of dust that will create an anaerobic layer roughly 2 layers of scoria thick, which is so dense that when you go to remove said scoria it is ike its set in concrete - thereby surely not allowing any water flow through it.

(?) i think that was a question, but so long i forgot.

Gunagulla

I'm not sure anyone suggested not washing it! I certainly give it a blast with the 25mm hose, and it puts out a lot of water at 250kPa, washing almost all the fine stuff away.

signore

I used one of these garden sieves and a wheelbarrow full of water to wash mine got almost 4cm worth of sediment from 250l worth of rock. no idea if it makes a difference but I'm glad it's not in my system taking up space.

http://www.bunnings.com.au/icon-plastic ... s_p2961023

didn't take long to wash. maybe 20 mins. I put a paint filter sock full off polyester batting on the drain line of the grow bed to catch extra sediment once I turned the pump on. The water ran clear after about 2 hours.

SydneyChick

Yavimaya - I will definitely be rinsing the scoria don't worry.

Signore - I have two rainwater tank mosquito screens that look very similar to the garden sieve. I think to be on the safe side I will also tie some old stockings around the drain lines with some batting inside like you suggested.

SydneyChick

Woot woot! Now to start rinsing!

SydneyChick

Oh no!

I ordered the 10mm scoria because in my research on forums that seemed to be the popular size and I was thinking that would be the average size of the rocks with maybe a few bigger rocks.

But it's filled with really fine little rocks! Is this going to be too fine??? :cry:

Yavimaya

SydneyChick wrote:

Yavimaya - I will definitely be rinsing the scoria don't worry.

Signore - I have two rainwater tank mosquito screens that look very similar to the garden sieve. I think to be on the safe side I will also tie some old stockings around the drain lines with some batting inside like you suggested.

I also have those mozzie filter inlet thingies.

they dont do well, they will get rid of the stuff that makes your water red, but will let a lot of finer rock and larger dust stay in the system.

i suppose it depends on how well you think you need it washed.

Yavimaya

Gunagulla wrote:

I'm not sure anyone suggested not washing it! I certainly give it a blast with the 25mm hose, and it puts out a lot of water at 250kPa, washing almost all the fine stuff away.

sorry if it looked like i was having a go at you, i wasnt.

i just cant see the fill and tip method doing well, i have tried that myself and it didnt work, im yet to see a method listed on BYAP that i havent tried and plunge and rinse is the only method that does anything decent, but still isnt perfect..... when i washed my rock to go into my biofilter, when i threw the rocks in the water stayed clear, the rocks were clearly quite clean, but after a few months of use i jumped in when the water level was low, kicked some around and noticed scoria dust.... :wacko:

and since i have seen so many people here saying washing is a total waste of time.... but then so many say Bui is wrong, i couldnt help but have a shot at people who dont wash rocks.

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Calculating media required for growbeds

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