GaryD

Integrated Aqua/Vegeculture System (iAVS)

177 posts in this topic

Hi Scott,

 

 

 

Gary

Where did you see that filtration was effective and aeration was good? At the termination of crop, McMurtry was reporting a TAN of .7-1.1. Water was returned by the bed with only a 50% reduction in TAN and NO3. At times, aqueous TAN exceeded the LD50 for Tilapia.

 

Exceeding the LD50 is almost criminal. Of course, they're "only" fish, but we do have a duty to take care of them, right? 

 

Just because the fish survived, doesn't mean they thrived, were efficient, or were healthy.

 

And you're right Gary. You didn't report the 2.6FCR for McMurtry. It was Paul who typed that in. I assume he can type correctly.

Edited by smatthew (see edit history)

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I'll look for the brand on the sack tomorrow as I'm not at home right now. It's just generic 32% catfish food from the feed store, cost around 19$ a 50 lb bag.

Can't beat that price. I have used premium fish food and the Purina game fish chow with extra live bugs in the bash.. Lol.. Problem is that the game chow has a lot of dust inn it.. Not all is solid feed pellets like I would like..

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Hi Charles,

 

Your deficiency issues would have been fixed as well with a properly built soil wicking bed as well, as has been shown by Mr. Van der Werf with his many many trials with the Earthan Beds.

 

The deficiency issues were not related to sand beds.  Again, while your support for Mr Van Der Werf is admirable, you seem to lose your normal objectivity when it comes to anything that he says or does.  Contrary to your suggestion, there have not been "many, many trials of earthen beds" there have actually been relatively few "trials."  I can recall two situations that Paul has reported on……one defunct system at Coombabah State School…..and one very nice set of beds in a retirement village in New South Wales…..and there may be  a handful more that he has installed but not spoken much about.  

 

I think the best comparison would be to look at the soil biological hydroponic operations and wonder why they did not choose to use primarily sand. I imagine there are also these biological hydroponic operations on the receiving backend of aquaculture facilties. Mr. Van der Werf has definitely proven soil wicking beds impact through his extensive work with with his Earthan Beds.

 

If you look at the horizontal sub-surface flow constructed wetlands upon which the Earthan beds were based, you'll see that they actually did use sand.  I see no reason why you ought not use soil…..and Paul has successfully done that….but sand is the media of choice for people who build constructed wetlands.  Once again, the term "extensive work" is probably a bit of an exaggeration.  Not that it matters, because constructed wetlands have been successfully used in thousands of situations throughout the world…..so we knew that they worked (using sand) long before Paul came up with Earthan beds.

 

Due to Mr. Van der Werf's accounting of his observations of other's commercial experiences utilizing primarily sand within hydroponics and the reasons he has given that indicates the iAVS needs more long-term trials, then I suspect #2 is the more logical question that should be asked.

 

Actually, there was no "accounting of his observations of other's commercial experiences" except those of Mark McMurtry - all of which supported the use of sand.  Despite several requests, for links to the "multitude" of alleged situations, none was ever forthcoming.

 

The "iAVS needs more long-term trials" is the only part of your post that will stand any test of objectivity.  

 

Seriously Charles, if I'd dished this stuff up to you, you'd be all of me like a rash…..and rightly so.   Let me be clear (since this seems to be a day for misrepresenting sand culture), this is not about Paul, it's about the difference between fact and folklore.

 

 

 

Gary

Edited by GaryD (see edit history)

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 Since your proposition is premised on the wrong numbers, you may be attempting to deal with a problem that doesn't exist.

 

Wrong numbers? Gary, what numbers are you using?

 

 

 

Ok well found at least some information on the loading rate of the sand bed.

 

I can not say if the different sized systems were optimized for fish production or the feed rates were to suit the plant species grown.

 

Attached below is a capture out of this document:

http://aquaponicsnation.com/forums/topic/8952-water-quality-maintenance-and-mineral-assimilation-by-plants-influence-growth-of-hybrid-tilapia-in-culture-with-vegetable-crops/

 

Seems the maximum density of fish at harvest was 16.73kg/m3 with a great feed conversion ratio of 1.27 using a fish tank volume to growbed volume of 1:2.25 (fish:growbed)

 

Experiment 1 - Average density 15.99kg/m3 with 1.37 FCR and average harvest weight of 216 grams each

Experiment 2 - Average density 10.30kg/m3 with 2.16 FCR and average harvest weight of 444 grams each

Experiment 3 - Average density 13.89kg/m3 with 2.76 FCR and average harvest weight of 692 grams each

 

No info as to how hard they pushed the fish system.  The feed conversion appears to get worse regardless of the grow bed size with increase in fish size (even with decrease in density), though in each experiment (notably experiment 2) the feed conversion appears to improve with an increase in growbed size.

 

Experiment 1 and 2 would raise questions on its sustainability at a larger scale.

 

My assessment based on that set of data, every 1000 liters of water you may need at least 2500 liters of sand in the growbed to maintain a density and subsequent feed loading of 15kg of fish per 1000 liters.  Others report similar results with larger void space media like expanded clay and 20mm gravel.

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The deficiency issues were not related to sand beds.

 

 

How would you know this?

 

 

Gary, what grow mediums are the biologically driven hydroponic systems utilizing? What are the reasons for these outfits to not primarily use sand?

Edited by crsublette (see edit history)

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Contrary to your suggestion, there have not been "many, many trials of earthen beds" there have actually been relatively few "trials."  I can recall two situations that Paul has reported on……one defunct system at Coombabah State School…..and one very nice set of beds in a retirement village in New South Wales…..and there may be  a handful more that he has installed but not spoken much about.  

 

And each of those trials did not show any nutrient deficiencies as well.

 

 

 

Sand is the media of choice for people who build constructed wetlands.  Once again, the term "extensive work" is probably a bit of an exaggeration.  Not that it matters, because constructed wetlands have been successfully used in thousands of situations throughout the world…..so we knew that they worked (using sand) long before Paul came up with Earthan beds.

 

Gary, what grow mediums are the biologically driven hydroponic systems utilizing? What are the reasons for these outfits to not primarily use sand?

 

 

it's about the difference between fact and folklore.

 

The difference appears to between what Dr. McMurtry says and what "others" are doing. After 20+ years...

 

Can you cite any further research done on the iAVS that did not involve Dr. McMurtry?

 

 

Gary, are there any honest, sincere, reasonable concerns for folk to disagree with the iAVS system? If so, please list 5.

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Hi Charles,

 

I was all but ready to abandon media all together before Mark showed up due to constant issues with deficiency of minerals. That went away with the sand and leaves me with two options that I currently considering. 

1  that something about the sand bed configuration increased the nutrients reclaimed. 

2  sand had stored nutrients in it.

 

 

Gary

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II was all but ready to abandon media all together before Mark showed up due to constant issues with deficiency of minerals. That went away with the sand and leaves me with two options that I currently considering.

    1  that something about the sand bed configuration increased the nutrients reclaimed.

    2  sand had stored nutrients in it.

 

 

This simply tells us that media beds do not allow sufficient support for microbiology.

 

You are attempting to suggest this is unique to the sand, which it is not since it is also found with soil wicking beds as well.

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And each of those trials did not show any nutrient deficiencies as well.

 

That's not in dispute.

 

Gary, what grow mediums are the biologically driven hydroponic systems utilizing? What are the reasons for these outfits to not primarily use sand?

 

​From the little that I understand about such system, I'm guessing that it's….SOIL.  Right?  One good reason that comes to mind, is that of organic certification.

 

The difference appears to between what Dr. McMurtry says and what "others" are doing. After 20+ years...

 

And I've told you what happened when Mark went to Africa.  Everything else is conjecture and speculation.

 

Can you cite any further research done on the iAVS that did not involve Dr. McMurtry?

 

No.  Can you point me to research (using the scientific method) that has been done on Raft?

 

Gary, are there any honest, sincere, reasonable concerns for folk to disagree with the iAVS system? If so, please list 5.

 

You're probably asking the wrong person…..but the big one that comes to mind is the uncertainty around the long term viability of the medium - the possibility that it might become corrupted and may need to be changed out.  After that, you could conduct comparative trials around a thousand aspects of sand culture…..as Mark has suggested.

 

I repeat…..he never set out to optimise anything.  His goal was to create a system which could be applied by un-skilled labour - in the harshest of conditions - that would put real food in their stomachs and he achieved that - in spades.  He has freely acknowledged that everything about iAVs could probably be improved/optimised.

 

Rather than think in terms of concerns, I think the better question is to ask how we might make it better.

 

 

 

Gary

Edited by GaryD (see edit history)

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This simply tells us that media beds do not allow sufficient support for microbiology.

 

You are attempting to suggest this is unique to the sand, which it is not since it is also found with soil wicking beds as well.

 

No….I'm simply making the point that Ravnis was talking about media (gravel) beds……not sand and not soil.

 

I haven't said anything about soil - one way or the other.  

 

Comparisons between sand and soil are meaningless as long as one is watered from above and the other is watered from below.  That's the functional equivalent of comparing chalk and cheese.  The efficacy of iAVS relies on the watery solids percolating down through the media. 

 

Gary

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And I've told you what happened when Mark went to Africa.  Everything else is conjecture and speculation.

 

Dr. McMurtry would not have to be present for further study to be conducted on his system.

 

Him being in Africa is quite irrelevant since his material was still quite public from the University to anyone to further validate and I bet Dr. McMurtry would entirely welcome.

 

 

No.  Can you point me to research (using the scientific method) that has been done on Raft?

 

I can point to Dr. Rakocy and Dr. Savidov and, if I had to do some research, I bet ya I could find more.

 

Can you point me to ANYONE doing research on the iAVS that did not involve Dr. McMurtry?

 

Mora & Garrett for example found quite easy to try to further research the system, except only did for 16 months (unless you know better) and we do not even know if the iAVS is in play by any business (not event a single name).

 

 

You're probably asking the wrong person…..but the big one that comes to mind is the uncertainty around the long term viability of the medium - the possibility that it might become corrupted and may need to be changed out.  After that, you could conduct comparative trials around a thousand aspects of sand culture…..as Mark has suggested.

 

So, there is zero short term concerns you can come up with at all?

 

The FCR, as Mr. Van der Werf pointed out due to using Dr. McMurtry's own data, and the issues stated by Mr. Smatthews would also be a reasonable concern, but quite odd you did not cite this as a concern.

 

 

I repeat…..he never set out to optimise anything.  His goal was to create a system which could be applied by un-skilled labour - in the harshest of conditions - that would put real food in their stomachs and he achieved that - in spades.  He has freely acknowledged that everything about iAVs could probably be improved/optimised.

 

Yet, it involves sand at a particular size that such countries may have a hard time to find

 

 

What could be improved/optimised?

Edited by crsublette (see edit history)

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Gary, I'm still waiting on your reply. Is exceeding the LD50 for an animal in your care failing to meet your duty of care?

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Hi Scott,

 

Sorry I didn't see the post…..I had to go looking for it.

 

Where did you see that filtration was effective and aeration was good? At the termination of crop, McMurtry was reporting a TAN of .7-1.1. Water was returned by the bed with only a 50% reduction in TAN and NO3. At times, aqueous TAN exceeded the LD50 for Tilapia.

 

No fish died during any of the trials…..so we can (in the absence of evidence to the contrary) only assume that conditions were (at least) adequate.  You've misunderstood the significance of "only a 50% reduction in TAN and NO3".  That reduction was with each pass of the water through the beds. Not only is that not a problem; it's actually a very good ammonia removal rate.  NO3 is nitrate and, as such, represents no threat to tilapia at any conceivable level.

 

My understanding is that, for anything to have exceeded LD50, 50% of the subject species had to die…..and nothing like that ever happened.  In any case, the pH in the system was usually in the region of 6.0 to 6.4…..in which circumstances the ammonia is in its less toxic form.

 

Exceeding the LD50 is almost criminal. Of course, they're "only" fish, but we do have a duty to take care of them, right?

 

I don't argue that fish are "only fish" but you haven't demonstrated that the fish were at risk much less harmed. 

 

Just because the fish survived, doesn't mean they thrived, were efficient, or were healthy.

 

Their growth rates…..and the absence of mortality…..and the absence of evidence to suggest that they were in any way stressed……and your failure to interpret the data…….would suggest that they were healthy.

 

And you're right Gary. You didn't report the 2.6FCR for McMurtry. It was Paul who typed that in. I assume he can type correctly.

 

I can't presume to know what Paul did…..and nor do I make any assumption about that.  I simply stated that I did not provide the figure.  In any case, I stated where I got my numbers from.  I only became aware of the numbers that Paul provided when Charles drew my attention to it.

 

Let's remember here, that Mark was engaged in research.  

 

He was comparing different fish tank volume to bio-filter volume ratios…..using the scientific method.  He sought to understand that the optimum ratio was…..while maintaining identical conditions….in terms of the weight of fish biomass, type/amount of feed, etc…...in each of the four systems.  

 

He didn't say that they any/all were optimum…..he just reported on what was happening in each of four different situations.

 

Your use of the term "criminal" is probably libellous in this situation.

 

Gary

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Went back through the few pdfs posted here

 

FCR in those were 0.8 to 1.3  with acknowledgement that tilapia were consuming algae grown in the water(this fact is probably the single fact that makes tilapia desirable)

 

What are you basing your point that he was at LD50 with TAN,  worst Data point I saw was a max of 1.5.

 

With a TAN of 1.5 mg/l and ph of 7 (highest I found) and temp of 30C   unionized level would be 0.012 ppm

Edited by Ravnis (see edit history)
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Dr. McMurtry would not have to be present for further study to be conducted on his system.

 

Him being in Africa is quite irrelevant since his material was still quite public from the University to anyone to further validate and I bet Dr. McMurtry would entirely welcome.

 

Charles, are you seriously hinging your argument against sand on the premise that I don't know why no-one took it up after Mark left for Africa.  How the hell could I know the answer to that question.  Who else could possibly know the answer.  In the absence of any evidence, there's only conjecture.  When Mark left for Africa, Dr Mora and Tim Garrett built their greenhouse and operated it successfully for 16 months.   That's all we know…..the rest is supposition.

 

He didn't require further validation.  He'd already determined what he needed to know and he took that information with him to the target audience for whom he'd undertaken the research…..the impoverished villagers of the sub-Sahara and the Middle East.   He probably didn't care what other people might think about it all then…..much less now.

 

And you're right, he would have welcomed further investigation.  Indeed, he wonders why no-one (that he's aware of) followed it up.

 

I can point to Dr. Rakocy and Dr. Savidov and, if I had to do some research, I bet ya I could find more.

 

To the best of my knowledge, Dr Rakocy essentially repeated the same thing for 25 years.  He proved that it worked…..to the extent that it did…..25 years in a row.  He never (to the best of my knowledge) ever compared what he did with sand culture or other plant production methods.  It could be argued that Jim was running a self-funded training program rather than conducting research as such.

 

Can you point me to ANYONE doing research on the iAVS that did not involve Dr. McMurtry?

 

​No…..but then nor (it seems) can anyone else.  McMurtry demonstrated that it worked.  It now falls to someone else to prove the opposite…..if they have the interest, the time and the money……or it's nothing but BS.

 

Mora & Garrett for example found quite easy to try to further research the system, except only did for 16 months (unless you know better) and we do not even know if the iAVS is in play by any business (not event a single name).

 

They took what Mark did…..and, straight out of the box, made a success of it.  Once they'd expended their grant money, they were no longer obligated to do anything with and they resumed their normal lives.  Let's remember that Dr Mora had actually retired prior to taking on the aquaponics greenhouse project.  Once he'd met the conditions of the grant, he went back to retirement.

 

So, there is zero short term concerns you can come up with at all?

 

The FCR, as Mr. Van der Werf pointed out due to using Dr. McMurtry's own data, and the issues stated by Mr. Smatthews would also be a reasonable concern, but quite odd you did not cite this as a concern.

 

The suggestion that anything about the research was "criminal" was laughable at best and libellous at worst.  In any case, taking one set of numbers out of context proves nothing.  Suffice to say, without even knowing what those numbers relate to, these were comparison studies.  In isolation, they do nothing to support your case (whatever that was).

 

Yet, it involves sand at a particular size that such countries may have a hard time to find

 

Actually, the fact is that Mark specified a median size of 0.7 (or similar) - that was the median size.  The sand that he used contained smaller and bigger particles (in the proportions that the document that I referenced in an earlier post.  I have no idea which countries would find his preferred particle size difficult to find.  My crystal ball doesn't take full account of all of the hypotheses that you seem to be able to put your mind to.

 

You (and your fellow sand-deniers :wink: ) seem to be going to inordinate lengths to discredit the work of a bloke whose only crime was that he set out to develop a food production system that was efficient in its use of water and that could put protein on the tables of impoverished villagers……and he succeeded.  For some reason, that doesn't rest well with people.

 

The other possibility is that your problem is with me…..and I'm good with that, too.

 

You appear to be determined to batter me senseless with the sheer volume of red herrings….but you're  consumed with the could and the should….and the might…..rather than dealing with what is…..and you've all failed to make a cogent case against……anything!

 

What could be improved/optimised?

 

Pick something?  We could optimise feed conversion ratios…..we could identify specific plant species that are pathogen-resistant…..we could test sand particle size to see what the optimum was.  We could do a thousand things….but it all starts with a baseline….and in Mark McMurtry's work we have that.

 

 

Gary

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I agree with Rupe, nice Kellen!

Seems like some of you just like to argue for the sake of arguing. Just build the sand beds if that's what you think works well. Ravnis did build one and so far, from what I have seen, it seems to work very well for his plant growth.

I would love to hear the thoughts of Mark on what he belives the reason was for the excellent growth and what seems to be much less deficiencies than that of other growing methods.

My guess is a combo of higher microbial activity and with that comes a release of minerals from the sand.

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Your use of the term "criminal" is probably libellous in this situation.

 

Gary

Gary, please stop changing what I said. I said it was "almost criminal". Stop paraphrasing what I said in an attempt to make me look bad.

 

PS: You don't think hitting LD50 levels are bad? Perhaps Kellen can help us out. Kellen - if you kept your fish at LD50 Ammonia levels - would that affect the health of those fish? Wouldn't that also be indicative of improper filtration?

Edited by smatthew (see edit history)

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After 20+ years... I find the volume of years involving of inaction meaning much...

 

 

Where are the 4+ year studies indicating the iAVS viability?

 

 

 

So then, returns to what I stated previously...

 

 

The Mora/Garrett was only for 16 months with USDA grant money and we do not even have the name (not even the name) of the business whom bought this system from them nor if the business has maintained the system as iAVS.

 

Most of these aquaponic operations function due to the niche market yet this has not stopped other aquaponic operations from squealing about their success. So this concern about "intervening competition" is horse hockey.

 

 

If the iAVS system is working fabulously well, then the business world would be expanding, involving more PR, and making News. Yet, where is this?

 

Is there the suggestion that "fear from dwc aquaponic agribiz" is keeping the iAVS establishments in the shadows? Come on...

 

 

 

I'd welcome evidence to the confirmation that the system is great outside of the realm of research and hobbyist perspectives....

 

Mr. Van der Werf did not say there were accessible studies. He was simply stating his observations from the experiences of other establishments that have used sand for more than 2 years. Due to Mr. Van der Werf's extensive immersion within successful commercial agriculture (i.e., hydroponic and aquaculture), I weight his observations with far more credibility than I do compared to someone whom has mostly spent their time behind academic or hobbyist walls.

 

BTW Gary, the longterm "possible" concerns you seem to now have was due to what Mr. Van der Werf introduced in context of long termin viability and how the sand might eventually must be managed.

 

Only so much "studies" can you tell... However, due to lack of public News worthy press on the iAVS and lack of business uptake of this method, then common sense tells me this system is not ready to leave the "studies" realm. Unfortunately aspect of "studies", they do not involve "common sense".

 

 

Gary, the burden of proof to prove iAVS viability outside of "studies" and "backyards" is entirely on the "iAVS band wagon" crowd.

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My guess is a combo of higher microbial activity and with that comes a release of minerals from the sand.

I think this, that is microbiological density and sand type (although not unique to sand beds), is responsible for the plant growth.

There is all types of sand which is indicative of their CEC, calcareous sand, non-calcareous sand, iron enriched sand, black sand, "sweet" sand, salt sand, etc., etc.

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Either way I think trying a sand bed with Paul's dual loop design would be very interesting. Feed liquid straight from the mineralization tank to sand bed. Or dose from MT as needed straight into grow bed loops sump and pump it to grow bed from there.

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You've misunderstood the significance of "only a 50% reduction in TAN and NO3".  That reduction was with each pass of the water through the beds. Not only is that not a problem; it's actually a very good ammonia removal rate.

 

What the... "50% TAN reduction per bio-filter (i.e., grow bed) pass" is deemed "very good ammonia removal rate".  This should be near 100%.

 

I remember this argument used against the CHOP2 design.

 

So now, since Dr. McMurtry is involved with positive trials, returning 50% TAN back to the fish tank is a GOOD thing?

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Nice critique Kellen.. ;)

 

And it would be a relevant critique if this was still the 1980s. ;)

 

 

All things considered, I think the FCR's that Dr. McMurtry achieved in his experiments are pretty good, considering when they were done, the parameters involved and the kind of tilapia that were used.

 

Since I am getting tired of all the lip service... Lets put some action behind this...

 

 

Mr. Weissenbach, with what you know now.... not in the 1980s..... In year 2015.... 

 

 

Is the iAVS system qualified and throughly tested enough for you to honestly, sincerely, and professionally place your name behind it to recommend the iAVS (as is defined) as a suitable alternative for a fella seriously looking into building an aquaculture farm with a horticulture backend return option?

Edited by crsublette (see edit history)

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Hi c

What the... "50% TAN reduction per bio-filter (i.e., grow bed) pass" is deemed "very good ammonia removal rate".  This should be near 100%.

 

I remember this argument used against the CHOP2 design.

I don't remember this argument against the CHOP2 design ?

The argument was allways that it returned some of  the water un-filtered only churning the solids, so no reduction of TAN

http://aquaponicsnation.com/forums/topic/4017-chop-2-aquaponics-system-layout/

cheers

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