GaryD

iAVs.info - the Integrated Aqua-Vegeculture System

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Why are sharp edges desired over round?  I would have thought it would be more prone to compaction and decrease in air void space (will always have a space between spheres)

the air spaces between spheres are tiny and the sand will move to fill any voids because the particles do not grip and hold each other in an open lattice.

 

when I was a kid we always dug our own sand, as far as i could tell the sand testing always involved muttering and scowling and grunting (with me doing the digging), then you wet the sand and feel it between the fingers and grunt and mumble some more, run it through a screen or wash it, inspect it again raise the eyebrows suck some air between the teeth (like a mechanic with a high quote to fix your car) and say "bugger it,that-all do. it seemed to work cos I had a reputation for the worlds toughest concrete.

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As an aside, Mark asked me who Yahoo2 was.

 

When I told him that Yahoo was a farmer from the West coast of South Australia (a hard place to farm), he responded with…."That figures.  He nailed the sand thing absolutely."

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I've posted another article on the iAVs site - "Dare to Compare - for the Layperson."

 

We've calculated that iAVs is conservatively capable of generating $500 per square metre (wholesale prices exclusive of income from fish or intercrops) - based on what it has already demonstrated.

 

We've also issued a challenge to anyone who can provide verifiable data for any food production system that is equal to (or better than) iAVs.

 

Gary

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Whatever happened to 'always use a solids filter before the bio filter'? So now we're back to just dumping it all in the media beds but with a finer medium that clogs more quickly!

And how is it that sand instead of gravel now magically fixes iron deficiencies? As far as I'm aware iron is only fixed anaerobically which suggests that your sand beds actually have large anaerobic areas.

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I will admit that I don't fully understand the processes that occur in the sand bed, that don't seem to occur in the gravel bed.  What I have noted is   blossom end rot in the gravel bed on my zucchini plant, but good fruit in the sand bed without visible blossom end rot.  Yellowing of the leaves has been an intermittent problem  in the gravel bed, but not in the sand bed. 

 

My guess is that the schmutzdeke more thoroughly breaks down the solids, thus making more nutrients bio-available.  I've only been trialing the sand bed since late october, so don't know the long term effects, but short term as a growing system it is closer to the system I originally thought aquaponics was:  add fish, add plants, feed fish, and harvest.    I did have to add boron for my broccoli though, so it's not completely without needing some additions, but much better that other methods I've used.  .

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Where I live, "washed construction sand" is referred to as "washed torpedo sand."  I have no idea why.

 

@ averan Those of us who are experimenting with this have the same perspective you describe.  But Mark claims it works so why not give him the benefit of the doubt.  The "oxidizing at the surface" seems like a plausible clog-prevention strategy to me.

 

I'll hopefully have mine built mid-summer.

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My questions are directed at Gary. Besides, there are loads of people claiming all sorts of stuff online, doesn't mean I can't have a few valid questions, especially when we collectively have years of experience (and forum posts) that contraindicate the new methods being espoused. Most of us forum type people like to know 'why' and aren't the type to just take someone's word for it.

 

Lots of people with media beds can attest to algae and solids buildup on the surface of their media....whether the medium is looser and slower clogging gravel or more tightly packed fast-clogging sand.

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Whatever happened to 'always use a solids filter before the bio filter'? So now we're back to just dumping it all in the media beds but with a finer medium that clogs more quickly!

And how is it that sand instead of gravel now magically fixes iron deficiencies? As far as I'm aware iron is only fixed anaerobically which suggests that your sand beds actually have large anaerobic areas.

 

The sand bed in iAVs performs as both mechanical filtration and  biological filtration.  It's the only aquaponics model that does this successfully.  The intermittent watering cycle used in iAVs provides for a  pumping time of around 10 minutes and a drain cycle of around two hours…..during the day….so it does not clog.

 

The range of microbial interactions that occurs in sand (like soil) is many and varied.  Suffice to say, there were no problems arising from the "large anaerobic areas" of which you are "aware"…..apparently!

 

If you read the posts on the iAVs site, you'll get answers to all of your questions.  

 

In the meantime, however, let me point out that there's nothing about iAVs that is "magical."  We leave the "magick" to the basic flood and drain fraternity.  iAVs is the only aquaponics system in the world to have undergone the scientific scrutiny that is has, so magic plays no part in its construction or operation.

 

In recent days, we've posted information on what we believe (based on past performance) iAVs is capable of…..and we've issued a challenge for anyone to draw our attention to any other system that is equal to (much less better than) iAVs.  

 

So far, there's been no takers.

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My questions are directed at Gary. Besides, there are loads of people claiming all sorts of stuff online, doesn't mean I can't have a few valid questions, especially when we collectively have years of experience (and forum posts) that contraindicate the new methods being espoused. Most of us forum type people like to know 'why' and aren't the type to just take someone's word for it.

 

Lots of people with media beds can attest to algae and solids buildup on the surface of their media....whether the medium is looser and slower clogging gravel or more tightly packed fast-clogging sand.

 

You can ask as many questions as you want……and any forum member is welcome to post on any matter they choose.

 

Contrary to your suggestion, there has never been anything like iAVs (other than iAVs) discussed on any aquaponics forum.  

 

As I pointed out in my previous post, the sand is a very effective filter…..both for snaring the solids and for nitrification.  In fact, there's nothing that even comes close in terms of cost-effectiveness and efficacy.

 

Feel free to point me to all of the sand beds with their "more tightly packed fast-clogging sand."  In any case, I think I've answered the question about  why the sand in iAVs doesn't clog.

 

The more I work with iAVs (and its creator), the more I'm convinced that it's the ultimate aquaponics system…..there's nothing you can take away from it - nor anything you can add to it - that would make it better.

 

It's simple enough for anyone to understand, it costs little (compared to any other aquaponics system), it's easy to operate, it out-produces anything that's happened since, it uses less water, it's more sustainable…….It ticks every box.

 

All you need to do, Averan, is build one.  It really is that simple.

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Hi Matt,

 

I wonder if fungal activity is much more improved in sand beds?  Does Mark talk about this at all Gary?

 

He acknowledges that he doesn't know the full range of microbial interactions that occur…..except to say that they are probably not dissimilar to those that occur in soil.   Sand + organic + microbes = soil.

 

If it's any different, he'll set me straight.

 

Gary

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The more I work with iAVs (and its creator), the more I'm convinced that it's the ultimate aquaponics system…..there's nothing you can take away from it - nor anything you can add to it - that would make it better.

 

It's simple enough for anyone to understand, it costs little (compared to any other aquaponics system), it's easy to operate, it out-produces anything that's happened since, it uses less water, it's more sustainable…….It ticks every box.

 

All you need to do, Averan, is build one.  It really is that simple.

 

Can you document, post pics of your build and work with iAVs please Gary

Edited by RupertofOZ (see edit history)

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Fwiw, I read all the blog style posts over there...There were no clear answers and I had to deduce several things about your system design. I don't know why you couldn't just state that it's aquaponics with sand as the medium. There's just pages of bullet point benefits.

So you pump for ten minutes, suck out all the fish poo and dump it on top of the sand to dry out for two hours. There it cakes and crusts and decomposes and somehow never clogs...and you don't actually know how.

Sand filters are nothing new, they've been used in koi ponds for a long time now where they don't have your magic and need to break up and clean out the poo crust that forms.

I notice you avoided my question. Gary, you have been a very vocal supporter of solids filters and now you want us all to pretend you never said any such thing. You might convince a lot more people if you explained how you turned a full 180 on this. How was your very strong opinion changed?

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I'm sorry if I sound bitter or combative, I actually really like the idea and just want some straight answers. I don't have the luxury right now of building and testing for myself, which of course is always the ultimate 'proof'.

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Starting to find more tidbits digging around the site:

"In 2014, aquaponics pioneer Dr. Mark R. McMurtry appeared on the Aquaponics Nation forum of which I was a member – and former owner.

For me, this was a defining moment because, in the ensuing days, a story began to unfold that virtually tipped everything that I thought I knew about aquaponics on its ear."

Care to share that story? :)

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Can you document, post pics of your build and work with iAVs please Gary

 

I was referring to my collaboration with Mark.....but then you knew that when you asked the question......which raises the question "Why did you ask it?"

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Well no I didn't actually, haven't been on the forum for weeks.... and just skim read the most recent posts

 

Given your empassioned embrace of the iAVs, and your comment about "working with iAVs"... I assumed that you had, or were doing so

 

If you're not... then why not?

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Well no I didn't actually, haven't been on the forum for weeks.... and just skim read the most recent posts

 

Given your empassioned embrace of the iAVs, and your comment about "working with iAVs"... I assumed that you had, or were doing so

 

If you're not... then why not?

 

I've embraced iAVs because of its efficacy.   In so doing, I should point out that's there nothing starry-eyed in my support for the process.  I don't get soft and fluffy about anything much.....and least of all with food production systems.  I genuinely struggle to find issue with iAVs.  Just when I think I could do something better, the intrinsic 'fitness for purpose' of the design drags me back to its raison d'être....and it remains intact.

 

In response to "the why not?".......let me say that it's still high on my agenda.  

 

In recent weeks, however, I've collaborated with Mark to build the iAVs site......and I've completed a Permaculture Design Certificate......and I'm talking to Dr Paul Olivier about a Natural Farming model suited to the Australian context......and I'm building a Microponics/Natural Farming/Permaculture/iAVs demonstration micro-farming on Macleay Island.....and, in my spare time, I'm posting on APN - doing what I've done for the past eight or nine years.

 

Now that we have a useful body of work on the iAVs site, I hope to introduce iAVs to targeted individuals and organisation in the hope that I can encourage new trials.  There's still a great deal to learn about the system.

 

And I'm hoping, in the midst of all of that, that I can build a "carpark" version of iAVS.

 

So.....care to tell us what you've been up to?   Anything interesting happening in your world?

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So.....care to tell us what you've been up to?   Anything interesting happening in your world?

 

Well apart from driving 1000's of kms delivering 1000's of rainbow trout fingerlings, hyper-extending my knee and chipping the bone during an ungraceful dive into a client's swimming pool system.... not much, other than hobbling around and taking a few photos...

 

About to do a total redesign on my system though... with the possibility of removing the media beds altogether.... I will post accordingly... ;)

 

In the mean time, just for the sake of it... here's a couple of sun rises to cheer up your day

post-3396-0-11828900-1432796311_thumb.jp

post-3396-0-89019900-1432796334_thumb.jp

Edited by RupertofOZ (see edit history)
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Fwiw, I read all the blog style posts over there...There were no clear answers and I had to deduce several things about your system design. I don't know why you couldn't just state that it's aquaponics with sand as the medium. There's just pages of bullet point benefits.

 

With respect, you clearly didn't read enough…..and contrary to your perception of it as "aquaponics with sand as the medium" does it little justice.  It's the progenitor of all aquaponics systems.  While we do describe the benefits of iAVs, we offer a considerable amount of data…..and even some water colour renderings of what one might look like in the arid environment for which was designed.

So you pump for ten minutes, suck out all the fish poo and dump it on top of the sand to dry out for two hours. There it cakes and crusts and decomposes and somehow never clogs...and you don't actually know how.

 

I know how it works and I've described its operation in this thread if you'd just make the effort to read it.

Sand filters are nothing new, they've been used in koi ponds for a long time now where they don't have your magic and need to break up and clean out the poo crust that forms.

 

We never said sand filters were new…..and we don't think there's anything magic.  As it said in an earlier post, we leave the magic stuff to others.

I notice you avoided my question. Gary, you have been a very vocal supporter of solids filters and now you want us all to pretend you never said any such thing. You might convince a lot more people if you explained how you turned a full 180 on this. How was your very strong opinion changed?

 

Averan, I have not changed my stance of filtration…..and iAVs is, in no way, in conflict with that position.   I'm not trying to convince you of anything and I'm not obliged to answer your questions.   If you want information from me, demonstrate some basic courtesy.

 

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The sand bed in iAVs performs as both mechanical filtration and  biological filtration.  It's the only aquaponics model that does this successfully.  The intermittent watering cycle used in iAVs provides for a  pumping time of around 10 minutes and a drain cycle of around two hours…..during the day….so it does not clog.

 

The range of microbial interactions that occurs in sand (like soil) is many and varied.  Suffice to say, there were no problems arising from the "large anaerobic areas" of which you are "aware"…..apparently!

 

He acknowledges that he doesn't know the full range of microbial interactions that occur…..except to say that they are probably not dissimilar to those that occur in soil.   Sand + organic + microbes = soil.

 

The clogging, or non-clogging of the sand beds in iAVs is the issue that has always had me scratching my head... and it seems others as well...

 

I can't understand how  "The intermittent watering cycle used in iAVs provides for a  pumping time of around 10 minutes and a drain cycle of around two hours…..during the day….so it does not clog.

 

How does the pumping interval effect, or as suggested, prevent the issue of clogging... and what determines the most effective retention time in order that clogging is prevented....

 

Intuitively it would seem that a 2 hour period just wouldn't be sufficient to do so... especially given the feed rate and solids wastes associated with the suggested stocking densities...

 

I'm really (genuinely) struggling to understand what processes underpin what to me would seem the integral heart of the operational success of the methodology...

 

My second concern is, with again the suggested stocking densities and wastes production.... what level of oxygen demand does the unknown process place upon the system...

 

The corollary of which is... how is DO maintained within the system with what would appear to be a significant organic BOD.... when the system methodology is based upon passive aeration only... which appears, by most other accepted observations, to be beyond the ability of passive aeration to sustain the suggested stocking densities?

 

Gary, I ask these questions genuinely... not with any intention to just "poke a stick"

Edited by RupertofOZ (see edit history)

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This is very interesting. You still won't answer my questions, you just keep insisting all the answers are on your website even after I've made it clear that I am having difficulty finding them. With all due respect Gary, despite all your great experience and knowledge (that I truly admire) your continued avoidance of our most basic and obvious questions suggests strongly that you don't actually know the answers. Ironic how much you now sound just like all the aquaponic charlatans you love to bash.

For the record, I'm not just poking a stick either, my questions are genuine.

I guess I'll look elsewhere for simple straight answers.

Good luck Rupe.

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Been monitoring this thread and do not understand the defensive challenges agaist iAVs. I think there is merit to using sand but as none of those involved in the discussion have ever built one I take the same stance as I took when reading about dual loop systems...a healthy skepticism. I know exactly how much poop comes out of my 68 Talapa tank and throwing that into any medium, including sand seems problematic.

My skeptic nature was increased when one member here offered to build a large test iAVs system in coodination with Mark until Mark seemily for little reason sabotaged that plan. So that just put enough doubt in my mind to make me sit back and take a wait and see stance.

But I have no doubt that of all the media out there, course sand would be superior if the solids were filtered first. Can it work with the solids? IDK and hope someone here tests it.

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The clogging, or non-clogging of the sand beds in iAVs is the issue that has always had me scratching my head... and it seems others as well...

 

I can't understand how  "The intermittent watering cycle used in iAVs provides for a  pumping time of around 10 minutes and a drain cycle of around two hours…..during the day….so it does not clog.

 

​OK…..that could have been worded better.  

 

What I was trying to suggest was that there was plenty of time for the bed to drain between pumping events.  In each plant production cycle, there was a stage (while the plants were still not large enough to shadow the furrows) where algae would build up in the furrows.

 

The furrows are an important part of the iAVs system.  First, they keep the plant crowns out of reach of the water - thereby avoiding crown rot.   Since the water does not cover the "islands" air is always able to be drawn into the beds on the drain cycle. 

 

During the early stage of plant growth, algae builds up in the furrows.  To avoid any potential for clogging, Mark would drag a stick along the furrow and dislodge the algae.   This ceased to be an issue once the plants were sufficiently developed to shade out the furrows.

 

How does the pumping interval effect, or as suggested, prevent the issue of clogging... and what determines the most effective retention time in order that clogging is prevented....

 

As I said earlier, it was more about the amount of time for the beds to drain adequately…..and I can see how I probably confused things in that wording.

 

Intuitively it would seem that a 2 hour period just wouldn't be sufficient to do so... especially given the feed rate and solids wastes associated with the suggested stocking densities...

 

I'm really (genuinely) struggling to understand what processes underpin what to me would seem the integral heart of the operational success of the methodology...

 

I hope I've clarified that.  The extent that it is still not clear, ask more questions.

 

My second concern is, with again the suggested stocking densities and wastes production.... what level of oxygen demand does the unknown process place upon the system...

 

I'll seek more information around this but, suffice to say (at this point), the efficacy of the sand (as a filtration medium) is such that the sedimentary and suspended solids are trapped on the surface of the sand…..where, for most of the time, they are exposed to the air.  They are not drawn into the media (as would be the case with gravel or clay pebbles), so they do not impose the same BOD burden.

 

The corollary of which is... how is DO maintained within the system with what would appear to be a significant organic BOD.... when the system methodology is based upon passive aeration only... which appears, by most other accepted observations, to be beyond the ability of passive aeration to sustain the suggested stocking densities?

 

Mark has referred to "lo-tech" and "hi-tech" versions of iAVs……the difference between the two being that the "hi-tech" version had forced air aeration (air stones) where the "lo-tech" variant relied on cascading water returning to the fish tank for aeration.

 

Gary, I ask these questions genuinely... not with any intention to just "poke a stick"

 

And I've attempted to respond in a like manner.  I hope I've clarifed things but the extent that I may not have, please just ask more questions.

 

 

This is very interesting. You still won't answer my questions, you just keep insisting all the answers are on your website even after I've made it clear that I am having difficulty finding them. With all due respect Gary, despite all your great experience and knowledge (that I truly admire) your continued avoidance of our most basic and obvious questions suggests strongly that you don't actually know the answers. Ironic how much you now sound just like all the aquaponic charlatans you love to bash.

 

Your problem is not that I won't answer your questions but rather that you confuse the issue with your provocative and offensive posting style.  Stop the BS and you'll get the information that you need.  I've underlined that part of this particular post that is getting up my nose on this particular occasion…..just for your guidance.  Every post that you make contains something similar.

For the record, I'm not just poking a stick either, my questions are genuine.

 

Try asking a straight question….(without the provocative BS)…...and you'll get a straight answer.

 

 

 

Been monitoring this thread and do not understand the defensive challenges agaist iAVs. I think there is merit to using sand but as none of those involved in the discussion have ever built one I take the same stance as I took when reading about dual loop systems...a healthy skepticism.

 

Jim….as a fellow skeptic, I endorse healthy skepticism.

 

I know exactly how much poop comes out of my 68 Talapa tank and throwing that into any medium, including sand seems problematic.

 

I think that the difference lies in your wording "and throwing that into any medium".  The fish solids do not penetrate the medium but rather sit on top of it…...where they are exposed to accelerated decomposition in the oxygen-rich atmosphere that exists on the sand.

 

My skeptic nature was increased when one member here offered to build a large test iAVs system in coodination with Mark until Mark seemily for little reason sabotaged that plan. So that just put enough doubt in my mind to make me sit back and take a wait and see stance.

 

That's not quite what happened……and Mark is not the only person to disagree with that "member".

 

But I have no doubt that of all the media out there, course sand would be superior if the solids were filtered first. Can it work with the solids? IDK and hope someone here tests it.

 

it worked….and about that there is no doubt.   And it didn't just work once…..it worked on every one of the many systems that were built by Mark and subsequently by  Mora and Garrett.   Let me remind you that, in the ratio trials alone (upon which Mark's dissertation was based) there were 16 systems in play…..at the same time. 

 

The efficacy of iAVs is vested in the sand.    The sand is a perfect medium for trapping the solids (on the surface) where they are mineralised (in the presence of air containing 21% oxygen).  The sand (with its huge SSA) is also a perfect medium for nitrification.  It's those two things that separate sand from every other media type - and that includes water.

 

​

Edited by Gary Donaldson (see edit history)

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Got it. Sorry for letting my irritation get the best of me.

 

What I find interesting here, is that all the solids actually will decompose/compost while laying out on the surface. I now understand why the sand bed doesn't clog, because you always give the water alternate routes and solids aren't able to easily penetrate simply because sand is so densely packed.

 

But now I'm curious, we're basically composting right under the plants....with actively rotting fish poo easily accessible, are there any new health concerns we should consider? Like children touching it or attracting flies/vermin?

 

The other issue or limitation that I think I'm seeing with this otherwise great system is that these beds must be timed flood and drain. That requires a sump which can also be the fish tank, but only if the tank is lower than the grow beds. This is fine if you're building the system on dirt, but on a parking lot it's a lot more difficult. I've been focused on designing for urban locations where you can't dig down and where the fish tank is about 4 ft. tall. Wet sand weighs about 120lbs/cuft making it very challenging to elevate. Personally, I hate traditional sumps as they take up a lot of space without serving any extra functions. It's just something I've been struggling to integrate into my designs and situation.

 

The most useful bit of info I've gathered is that sand is a fabulous bio filter medium as well as a cheap/sustainable/renewable/widely-available growing substrate.

 

I really love the simplicity of the design concept and think it's perfect for low-resource third world type situations, but I'll have to keep working to figure out how best to apply it in urban settings.

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