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ITT we discuss Decoupled / Open loop / Multi-circuit aquaponics systems

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That may well be true Ande...

 

But are the anaerobic process integrated in the production line themselves... or actually "decoupled" and the end product returned/used....

 

I doubt they'd have their anaerobic digester in their RAS fish loop....

 

I'm not opposed to using an anaerobic digester .. to reclaim/reuse the resultant "sludge".. conversion into methane for lighting/heating... or even just composting it....

 

I just suggest.. (back several posts)... that it should be decoupled from any fish/plant/mineralisation loop....  there seems to be quite a few examples where that's not the case... ;)

You posted when I was posting

Offcourse they are decoupled any properly designed commercial RAS/PRAS would be .

 

cheers

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Agreed.. see post above as you were posting... and I said that before.... decouple it and leave it out the back... it has no place in the fish/plant/ mineralisation loops... or more specifically... no place "in-line"...

haha we post at the same time again :thumbsu:

yeah we are in agreement,

Edited by ande (see edit history)

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Nitrate reduction, however, may be an issue for some people.  As I've said, high nitrate levels in some foods are a health concern.   Most of us grow food for our own use (and that of our families and friends) so the last thing we want to do is produce food which is somehow unhealthy.  I can't think of practical examples off-hand but there may be plants that require little nitrogen (but all of the other goodies).

 

The old mantra of "add more grow beds" is not always practical or desirable……any more than is running a system at half throttle to limit nitrate production. 

 

That implies though Gary...  that the system is over stocked for the feed/waste production.....

 

Denitrifying is just band-aiding a more signification potential problem....that should be addressed...  ;)

 

The old mantra of "add more grow beds".. will by definition.. resolve/reduce both potential issues.. ;)

Edited by RupertofOZ (see edit history)

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Rupert,

 

As long as you're talking about attempting methane production, I agree with everything you've said.  The numbers just don't stack up for anything less than the largest aquaculture operations.

 

The "largest"  you talk about are more common zise here.  the methane production would be used on site for suplemental heating etc.

 

cheers

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Aside from the matter of methane production, I can see where an aquaculture operation (of suitable scale) might be interested in anaerobic digestion - just so that it could meet water quality requirements…..either for re-use on-site or for discharge into local waterways.

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Aside from the matter of methane production, I can see where an aquaculture operation (of suitable scale) might be interested in anaerobic digestion - just so that it could meet water quality requirements…..either for re-use on-site or for discharge into local waterways.

 

Totally agree Gary, and as Ande suggests progressive RAS operations and aquaculture countries are moving this way.. as part of their "zero discharge from property" best practice implementations...

 

Even in many cases replacing the previous reed-bed/simulated wetland and anaerobic retention pond policies... which were still possibly prone to flood events...

 

So why shouldn't commercial AP operations adopt anything but similar "decoupled" best practices.. ;)

Edited by RupertofOZ (see edit history)

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Had already done that and where the range had originally come from.   That document list kale, cabbage, collard, etc.

 

Found conflicting research from Cornell around the 5.6-5.8 level.  

 

Guess I shouldn't trust this chart either  http://www.gtghydroponics.com/faq/veggieph.aspx

 

The odd thing is I've seen great growth of greens at ph of 8 to as low as 6.   PH below 6 actually retarded growth in one system.  Make one wonder just really how important PH really is as a parameter.  Of course, great growth is not necessarily optimum.  Still it makes one wonder just really how important PH  is as a parameter

 

Like Mr. Oz said... it all depends on trace element take up... or lock out...

 

This can be easily offsetted by simply adding more fertilizer...

 

My farm has a water pH of 8.4, KH of 16, and a soil with a pH of 8.1 that has an immense amount of calcium and magnesium perma-locked into the carbonate soil particles... However, this has not stopped us from growing 260 bu/acre corn nor stopped onion and carrot fields here from significantly producing... How? Due to the fact that we add approximately 20~30% more fertilizer simply to compensate for the alkaline soil and alkaline water...

 

Ryan in his videos have said the same... simple test for ya... Take a Nitrate test at a pH of 8.0... Take a Nitrate test at a pH of 5.5... Nitrate will be showing through the roof at a lower pH....

 

These pH's related to plant growth is for plants and operators to do the least amount so they can produce the most amount out of the plant...

 

This is not to say that some plants will simply not perform... except there are plants that will simply not perform at more neutral pHs or higher.

 

Although... this is a far cry from saying that some plants "enjoy a higher pH"...

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That implies though Gary...  that the system is over stocked for the feed/waste production.....

 

Denitrifying is just band-aiding a more signification potential problem....that should be addressed...  ;)

 

The old mantra of "add more grow beds".. will by definition.. resolve/reduce both potential issues.. ;)

 

Not at all.  Denitrification might just mean that you want to rid the system of nitrates….for the reason that I've stated.  If you have a fish production system that is operating very efficiently, it will still produce nitrates.  Indeed, it will produce plenty of nitrates because the fish will be eating plenty and pooping plenty and the filtration system will be converting the fish wastes (no uneaten food happening in this system). 

 

If you have no need for those nitrates…..and no requirement for more plants…..then denitrification is a sensible option.  

 

Let's remember that we're talking about decoupled systems here.  This is about having the ability to customise your system outflow to precisely meet the needs of the plants in that system.  If we translate that into a commercial environment, plants are most often grown to fill orders that will have been placed well before the seeds were sown.  Growing more plants just to soak up excess nitrates may just be a waste of money.

 

So why shouldn't commercial AP operations adopt anything but similar "decoupled" best practices..  ;)

 

I think we're all singing off the same hymn sheet there.

Edited by Gary Donaldson (see edit history)

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Let's remember that we're talking about decoupled systems here.  This is about having the ability to customise your system outflow to precisely meet the needs of the plants in that system.  If we translate that into a commercial environment, plants are most often grown to fill orders that will have been placed well before the seeds were sown.  Growing more plants just to soak up excess nitrates may just be a waste of money.

 

But in a commercial scenario... you would have sized your plant component to utilize the maximum nitrate output.. or close to it... from the start...

 

You wouldn't be adding more seedlings/plants.. just to soak up an unexpected excess... unless you didn't size your plant production component appropriately in the first place.. or to put it another way.. over-sized/stocked your fish component...

 

Or if perhaps...  you were just making it up as you went along... :D

 

 

In a properly designed commercial system... you'd be more likely adding/harvesting fish cohorts.. to match your plant production... ;)

Edited by RupertofOZ (see edit history)

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Rupe,

Nitrate reduction if you built a system with too many fish would be one reason for denitrification :)

Or if you would want to have a RAS system free of plants and without water changes like the Grow fish anywhere systems by Mr Jaap Van Riijn.. What's up with all the Dutch guys doing aquaculture anyway? :D

Edited by SwedeAquaponics (see edit history)

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What about if the plant order was reduced?  You wouldn't feed you fish half as much just because your order was cut in half.

 

What about if it was changed from silver beet to bush beans (a legume)?  Would that lead to a reduction in the amount of nitrogen that was needed?

Edited by Gary Donaldson (see edit history)

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What about if the plant order was reduced?  You wouldn't feed you fish half as much just because your order was cut in half.

 

What about if it was changed from silver beet to bush beans (a legume)?  Would that lead to a reduction in the amount of nitrogen that was needed?

 

In a commercial system... unless due to some catastrophic crop failure... such changes would/should be minimal in impact on the RAS system.... even then only a temporary fluctuation...

 

Plants don't take long to grow... especially in a nutrient rich environment.. ;)

Edited by RupertofOZ (see edit history)

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What about if the plant order was reduced? You wouldn't feed you fish half as much just because your order was cut in half.

What about if it was changed from silver beet to bush beans (a legume)? Would that lead to a reduction in the amount of nitrogen that was needed?

What would use of a legume matter? Legumes only require less oxygen because of their relationship with sp. rhizobium. I don't see that existing in a growing system constantly bombarded with water.

Now in an Earthan bed...

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Anaerobic means completely without oxygen.. Anoxic is when there are still other oxygen available in the form of NO3 (as an example) So the bugs grab the oxygen from the nitrate to feed themselves. That's when denitrification occurs..please correct me if I am wrong

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That implies though Gary...  that the system is over stocked for the feed/waste production.....

 

Denitrifying is just band-aiding a more signification potential problem....that should be addressed...  ;)

 

The old mantra of "add more grow beds".. will by definition.. resolve/reduce both potential issues.. ;)

If your main product is fish, wich most often is the case around here,with a a natural advantedge, with plenty of water and "right temp" on some high end species.

Also  the natural, limitation on plants (light/heat), makes more grow beds, a werry expencive and often a non sustainable solution.

But a plant nursery/greenhouse, combined with outdoors seasonal crops, edible, ornamental, industrial, where you use parts of, or all the fish, (and plant) wastes as a fertilizer is sustainable in a 45min range/distance from densely populated areas like (city/suburbs), is sustainable given the proper design.

Much like The UAE project was located 15/20 minutes from down/town in Dubai city. (direct marked acsess) and had a fishculture add on, it all depends on the objective(s) in focus.

All over the western world we have some sort of water polution acts to comply with, so ap or IAAC is given the right sircumstanses, "the solution to polution" or at least can be, and/or are partly so.

 

and the industry is expanding explosively with a endless demand in a 30-50 years prospective so the large initial investment costs, are maybe not so large or risky  ?

 

 

 

cheers

Edited by ande (see edit history)

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Hi crsublette,

 

Correct me if I am wrong, but it appears that 90% of your posts in recent threads are related to maximum nutrient utilization... except where you say you dont care about degassing of nitrates....

Then I read this statement ...

 

Due to the fact that we add approximately 20~30% more fertilizer simply to compensate for the alkaline soil and alkaline water......

 

I am really having a hard time deciphering where you are coming from.

I also have to ask, how long do you feel such practice is sustainable for ?

 

Cheers

Joe

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Anoxic means "without oxygen"

Hypoxic means "low oxygen"

Anaerobic is a qualifier which refers to respiration (and some other processes, usually incorrectly ex. "anaerobic" fermentation) which occurs without oxygen.

The "bugs suck oxygen from other sources" is a bit of a simplification. There are certain bugs that will reduce NO3, like sp. Denitrificans and E. Coli. The end result looks like a bug eats the oxygen off, but it's a bit more complicated

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If your main product is fish, wich most often is the case around here,with a a natural advantedge, with plenty of water and "right temp" on some high end species.

Also  the natural, limitation on plants (light/heat), makes more grow beds, a werry expencive and often a non sustainable solution.

 

True Ande... but we're then making a distinction between commercial and backyard...

 

And you'd design, as you suggest and I said...  properly to match your plant production to your feed/waste output...

 

And you wouldn't be using media beds at all... :D

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What would use of a legume matter? Legumes only require less oxygen because of their relationship with sp. rhizobium. I don't see that existing in a growing system constantly bombarded with water.

Now in an Earthan bed...

 

OK….that seems reasonable (I'm assuming you mean less nitrogen).  

 

In a backyard situation, Earthan/Ultimate beds are a possibility…..and there is an other alternative about which I dare not speak.   ;)

 

Of course, if you were talking commercial you wouldn't be using Earthan beds (because I believe their architect has said that they are not practical for commercial use)…but methinks sand beds might be another matter.

 

There I did it……dropped the freakin' "S" word again. ;)

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Of course, if you were talking commercial you wouldn't be using Earthan beds (because I believe their architect has said that they are not practical for commercial use)…but methinks sand beds might be another matter.

 

I wonder if sand beds might have anaerobic processes....

 

And how would you tell.. and control them if they did... perhaps count the days.. or test the nitrates.. and then go and rake them.. :D

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