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Cutting IBC cage at 1 segment or two?
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Author:  seanmc980 [ May 7th, '13, 08:17 ]
Post subject:  Cutting IBC cage at 1 segment or two?
So I just landed 3 IBC's to start my project but I'm not 100% sure what level I should cut the cages. I'm doing a CHIFT PIST with SLO. I plan on using 10 IBC grow beds that are all running constant flood that drain into one sump. I see kind of a mixed bag for what level to cut the cages... one section seems too small and two seems too large.. I don't have the measurements but they seem to be about 10" from tube to tube. So the question... does anyone here regret cutting and setting up there IBC with one section vs two? Obviously cutting at 2 sections would add twice the depth for plant roots, but will add to costs with media and weight a significant bit more. Thoughts?
Author:  mantis [ May 7th, '13, 08:34 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
Just be sure they are 12" deep minimum and after that its your choice. My ibc system has three beds that are half ibcs so 50cm deep and there is a large system in Kalgoorlie that uses full ibc's as growbeds
Author:  bunson [ May 7th, '13, 08:35 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
You can cut the cage at one segment, but then cut the bottle slightly larger as the one section of cage will still provide support to the GB full of water and media even though some is above the cage level. The recommended minimum depth of media in the GB is about 300mm (~1 foot) but you'll need the GB to be 50-150mm (~2-6 inches) deeper than this else whenever you disturb the media when planting or harvesting your media will spill out across the floor!

If you're making a system with 10 GBs and you are going to be constantly flooded, I'd be cutting each of the 5 IBC in half (or closest thereto) to maximize the filtration capacity of the system, but as you mention there is a significant cost and weight to be factored in. What media are you intending to use? Is the system going to be installed above ground level (balcony, multi-storey building etc)? It can be possible to use a cheaper media as a base layer in the bottom of a GB with a "better" media layer in the top 300mm (depending on the types of media and activities in the GB, these may or may not mix over time) which may save some $$$. If this is not possible then aim to maximise the filtration.

How big is your FT going to be?
Author:  seanmc980 [ May 7th, '13, 09:05 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
Bunson, This media system is going to be the main bio filter for our DWC beds. This week we plan to setup six IBC beds. They'll be all lined up in a row, elevated 3 cinder blocks high with a sump underneath and another cut IBC underneath for an auto top-off. I'll throw a few coi in there once it's cycled. We haven't sources a FT yet but for now we can use a few IBC's. We plan to use 3/4" gravel for the bottom layer and either hydroton or expanded shale for the top. This setup in going on a small foundation on the back our property. This system is going to feed 15+ 8X4 raft beds. I feel that getting the media started ASAP will only make it that much quicker before we can sustain a system of this size.
Author:  seanmc980 [ May 7th, '13, 09:16 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
mantis wrote:
Just be sure they are 12" deep minimum and after that its your choice. My ibc system has three beds that are half ibcs so 50cm deep and there is a large system in Kalgoorlie that uses full ibc's as growbeds


I will aim for 12" minimum. I would think that an IBC full of media would either need to be on a F&D cycle or drain from the bottom to avoid a toxic build up in the bottom?
Author:  bunson [ May 7th, '13, 10:02 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
seanmc980 wrote:
I would think that an IBC full of media would either need to be on a F&D cycle or drain from the bottom to avoid a toxic build up in the bottom?

Nope. You just need to ensure there is an "adequate flow" of well oxygenated water through the media.

Water entering the media through the top and draining out the bottom will mix and avoid stratification; it's harder to create dead-zones than many people espouse, especially in a well-designed system. If you are particularly concerned, you could perform a complete drain of a GB on a regular basis as part of your maintenance routine.

Adequate flow is easily tested by adding a "stain" to the water such as Seasol/Maxicrop and observing where the water darkens during the pumping cycle.
Author:  DrLuke [ May 7th, '13, 12:59 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
Check out outbackozzie's commercial system (mantis mentioned it above). He used full IBCs for all his growbeds. He used a media guard that only had holes at the bottom. This forced the water down to the bottom, then back to the top of standpipe, to achieve flow through the whole media column.

I'm considering doing the same for my next system. Given the cost of an IBC compared to building two sturdy stands to hold half the IBC each, and the saved labour in halving the IBCs and building stands, Im liking the economy of using whole IBCs.

And if you are a "lotsa fish in little space" type guy/gal, then you will favor allocating more room to a big FT than to growbeds. So using full IBCs will double your filtration in the same footprint.
Author:  seanmc980 [ May 7th, '13, 21:57 ]
Post subject:  Re: Cutting IBC cage at 1 segment or two?
I would think that using half an IBC that forced water from the bottom would work best for maximizing your bacteria colonies.I'll check out his thread. I wonder if it's installed just like a bell siphon only without the cap, or a siphon break in place?
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