JeffH

Heredia, Costa Rica Prototype Build

69 posts in this topic

If what you 'really' want is "both worlds", then do both ... separately.    I makes no sense at all to me to compromise both without any possibility of improving either.   In addition, if you did both, you could compare each to the other.  If you bastardize both you can compare neither.  

Edited by GaryD
Unhelpful comment removed (see edit history)
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Thanks for your reply Mark, I do plan to do both when we move to our new location.

However, I'm curious what you and others think about the potential value of using nutrients leaving the iAVs bed for use in a deep water growing area where you might focus on plants more appropriate for that environment (e.g. lettuces). Do you think any key nutrients would be tied up in the sand and not accessible for a raft system further downstream? Perhaps a DWC system could be improved with an iAVs sand filter?

Edited by JeffH (see edit history)

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On 11/4/2016 at 8:57 AM, JeffH said:

Hi MT, I was curious about your note above about having to overload your fish tank in order for the system to flood properly. I am interpreting this to mean that without the extra waste being deposited on the grow bed, the water was making it all the way down the furrows because it would seep through too quickly? If this is the case, do you think it would have corrected itself once some biofilm built up on the furrows?

Indeed, the water simply disappeared into the sand and never flowed laterally on the surface. I'm sure this is because the sand was too coarse, which prevented solids build-up on the surface.  I wanted to see if I could "convince" the sand to flood by loading it with excessive solids, effectively reducing the drainage of the sand, and it appeared to work. 

It is possible that the system would have begun flooding on it's own eventually, as biofilm built up in the sand, but with air temps around 105F and water temps over 90F, the bacteria were working just about as fast as they could to break down the solids and clear the spaces between sand grains.

I also wondered if the flooding would continue once it had started, with a reduced level of solids, so I cut back feeding once the beds had been flooding for about a week.  The flooding ceased that day, and shortly thereafter I started pulling dead fish out of the system daily, until there were none left. 

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22 hours ago, JeffH said:

A question for iAVs-ers

Could an iAVs bed act as a solids and fines biofilter for a DWC system? I have been wondering if you could simply have an iAVs bed with perhaps a few plants, but definitely not enough to take up all the nutrients. Could the water then flow to a DWC bed for growing other crops? It seems like the iAVs bed does essentially what many DWC filter systems do. Would the sand hold back essential nutrients for the DWC section or would the water from the iAVs growbed contain enough?

Yes, I want the best of both worlds... :-)

I've thought about the same idea myself, especially when I overloaded my sand bed and the Nitrates continued to climb. I have to agree with Mark though, you're not likely to be improving on what you're already building. If you already had a DWC system, I would highly recommend adding a sand bed in line to capture solids.  This would keep the DWC troughs cleaner and improve mineralisation, and you would have a place to put some tomatoes or something else that doesn't do as well in DWC.

One problem with operation is the fact that DWC systems usually run continuous flow, but iAVs is an intermittent flood system.  You can operate the DWC this way, but you'd be relying entirely on your bubblers for water movement around plant roots, unless you add a circulation pump for just the DWC troughs themselves, which is just one more thing to deal with.

As far as nutrients being tied up in the sand, there's no reason why they would be held back once they are dissolved in the water.  The sand will trap solids, but it won't retain dissolved ions.  Any dissolved nutrients that aren't absorbed by plant roots in the sand when they are first liberated from solids will flow freely through the system until they are absorbed by the fish, bacteria, or plants.

When you say, "Best of both worlds," what do you see as the best of DWC that you want to carry over to iAVs, and what is the best of iAVs that you want to carry over to DWC?

Edited by MT Mind
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9 hours ago, MT Mind said:

Indeed, the water simply disappeared into the sand and never flowed laterally on the surface. I'm sure this is because the sand was too coarse, which prevented solids build-up on the surface.  I wanted to see if I could "convince" the sand to flood by loading it with excessive solids, effectively reducing the drainage of the sand, and it appeared to work. 

It is possible that the system would have begun flooding on it's own eventually, as biofilm built up in the sand, but with air temps around 105F and water temps over 90F, the bacteria were working just about as fast as they could to break down the solids and clear the spaces between sand grains.

I also wondered if the flooding would continue once it had started, with a reduced level of solids, so I cut back feeding once the beds had been flooding for about a week.  The flooding ceased that day, and shortly thereafter I started pulling dead fish out of the system daily, until there were none left. 

Hi MT,

Just reread the posts about your system and also saw that photo of your sand after sieving: gallery_4554_147_2070752.jpg

Looks way coarser than mine, I guess because I just washed mine so it has lots of smaller particles left:

30083435814_30ed4ded1d_z.jpg

So... I'm hoping it will work more effective as a filter. It's been a few days and while I can't see much of any biofilm yet, the furrows now fill about 2/3 of the way down. I'll post a pic tomorrow when it's light. This is useful though, because it is starting to demonstrate where the upper sand particle size limits are for the iAVs to function. Still haven't heard what is "normal" though in terms of when to expect the furrows to fully flood. 

PS Damnit, did you have to use a shiny quarter too? My sand looks so... industrial.

Edited by JeffH (see edit history)

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8 hours ago, MT Mind said:

I've thought about the same idea myself, especially when I overloaded my sand bed and the Nitrates continued to climb. I have to agree with Mark though, you're not likely to be improving on what you're already building. If you already had a DWC system, I would highly recommend adding a sand bed in line to capture solids.  This would keep the DWC troughs cleaner and improve mineralisation, and you would have a place to put some tomatoes or something else that doesn't do as well in DWC.

One problem with operation is the fact that DWC systems usually run continuous flow, but iAVs is an intermittent flood system.  You can operate the DWC this way, but you'd be relying entirely on your bubblers for water movement around plant roots, unless you add a circulation pump for just the DWC troughs themselves, which is just one more thing to deal with.

As far as nutrients being tied up in the sand, there's no reason why they would be held back once they are dissolved in the water.  The sand will trap solids, but it won't retain dissolved ions.  Any dissolved nutrients that aren't absorbed by plant roots in the sand when they are first liberated from solids will flow freely through the system until they are absorbed by the fish, bacteria, or plants.

When you say, "Best of both worlds," what do you see as the best of DWC that you want to carry over to iAVs, and what is the best of iAVs that you want to carry over to DWC?

Great point about pumping the water around. I hadn't thought of that! Although... you could have something like a bell siphon that would trigger the sand bed flood from something like an inline sump tank. So the water is continuously flowing but every so often, the sump tank (holding enough water to sufficiently filter the main system) would empty into the sand filter. The rest of the water would just bypass the filter. 

By best of both worlds (and this is totally newbie perspective!) I meant, having the ease of planting and harvesting greens (like lettuce, etc) in a DWC system while growing tomatoes, peppers, etc. in the sand. Having seen some DWC systems now, I can really appreciate the reduction in work/time for planting and harvesting crops like lettuce. Systems that use the "Cleverponics" rafts are pretty efficient! Plus, the chance of getting some sand/grit in low crops like lettuce has to be high. Nobody likes gritty salad :-) 

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I should mention that my system is still fishless...so not expecting a major biofilm to build up very quickly. But a thin layer of surface material, algae, bits of debris blowing in, etc. should, I would think, be enough to get the furrows to completely flood in another few days.

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Okay, here's an update after a week of pumping water from my fish-less tank. The furrows now flood about 3/4 of the way down the bed. Would still love to hear about anyone else's experience in terms of how long it took to evenly flood the sand bed.

The furrow on the right does have water in it too - it's just that the lighting makes it look empty.

30743957032_d0fd6a74ca_c.jpg

30772360091_5ec1700eec_c.jpg

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48 minutes ago, JeffH said:

Would still love to hear about anyone else's experience in terms of how long it took to evenly flood the sand bed.

15 minutes - first time, every time

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28 minutes ago, Mark McMurtry said:

15 minutes - first time, every time

Great to know. Thanks Mark. Guess that confirms that my sand is draining too quickly, at least compared to your studies.

I do find it surprising that the sand bed would saturate and flood so quickly unless the outflow was restricting the escape of water somewhat. Would you say that your drainage outlet was smaller than the inlet so that if you left your pump on for longer, the furrows would overflow? Or was the drain large enough that flooding the raised areas wouldn't happen?

Or perhaps the question is, should the sand be fine enough so that the flow through it is slow enough to cause flooding, despite having a large outlet?

Edited by JeffH (see edit history)

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Hi Mark, yes, I've seen those (helpful) pages. I think what I, and perhaps others, struggle with a bit is a more obvious way to test sand. I know about the "bucket test" but that is a bit vague. I wonder if there is a more accurate (and perhaps simpler) test that could be derived to better gauge the hydraulic conductivity of a sand source. Since being able to flood a furrow at a reasonable rate is a requirement, I wondering about filling a bucket part way with sand (say 4/5 ths) and then measuring the time is takes for 1/5 bucketful of water to completely seep into the sand, if poured quickly (a second or two). That way, one might get a better idea of how long a given volume of water might sit on top of the sand before disappearing beneath the surface.

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No offense intended to you or anyone else ... but I'm done attempting to define/explain sand and related performance criteria/variables..  I just do not know how to communicate in a manner that people can seemingly understand.  I'm SO very weary of this.  At times it appears to me the at least some if not most people just refuse to think and/or understand.  Not saying this is true in your case, yet I still do not know how to communicate.  I never had the slightest problem sourcing sand (in the US or in Africa).  Not claiming that everything I sourced 'worked' exactly the same ... I knew what was too fine an/or too course just by looking at it, playing with it in my hands, by making 'careful' observation.

I suggest that there is NO substitute for first-hand experience - while paying close attention to what 'behaves'/performs as desired and what does not.  Doing is learning and vice versa.  As I understand, you are aware that your media is far coarser than I've trialled.  Then how can it be any surprise that it does not behave/perform as desired?  Too fine won't drain well, too coarse won't saturate - duh.  This is SO basic/fundamental to me that I apparently can't seem to describe/explain it.  

I used/recommend what I've defined/described repeatedly every way I know.  The ATSM C-33 specification (US) 'worked' performed spectacularly for me.  This specification is used throughout the world (by different terms in various countries) to make structural quality concrete, whether in the US, Oz, China, Egypt or anywhere else.  It is not expensive or at all difficult to source - IMO.  It has clearly defined criteria such as NO carbonate or salts or silt and defined particle size distribution limits.  If you get material that meets this specification (not all vendors are competent, honest or knowledgeable but most who quarry for commercial contract work are) then it should work just fine - it always did for me.  I'm not claiming that it is the ideal - no one actually knows what the "ideal" is.  No one also knows what the limits are - how far one can deviate from what I tested/used and still achieve an adequate result - however defined. I know that I had absolutely NO problem whatever in sourcing or using sand that performed - more than adequately.  I obviously DO have a problem communicating.  

At this point, I'm SO sick of trying to 'define'/explain sand that I admittedly get angry (profound frustration)  just 'thinking' about it.  iAVs was 'about' people who needed a better/more reliable diet being able to accomplish/provide more security/vitality for themselves then they otherwise could in constrained circumstances/environments.  It is and never was about technology, equipment, hardware or devices - its biology and 'common sense' (which is obviously NOT common), and also not magic or woo-woo or 'technology'.  

I'll get off my soap-box now by concluding that it categorically amazes and shocks me that many if not most people seem to have grave difficulty understanding any of this (IMO in too many cases deliberately) and that at this juncture I feel it is now up to others to attempt to explain/describe the nuances since I am provably not able to do so.  I'm not suggesting that I want this to be the case, just that it is apparent - at least to me - that this is a fact.  How/why this is is open to conjecture and speculation - as is EVERYthing else wrt AP fantasyland IMO - is unfathomable to me.  

Edited by Mark McMurtry
typo, insert paragraphs (see edit history)
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Hi Mark,

I totally get your frustration. But remember that many of us are coming at this new and don't yet have the feel for the sand and its characteristics. The info you have on the iAVs website is fairly clear but it's also stated in several places that these are guidelines and not every combination/permutation has been tried. Those of us that come from a science background are interested in figuring out what kind of variations might work and have questions that, while obvious to you, arise because we haven't had the hands on experience with these types of systems. A great example is having a feel for how long the water should take to fill the furrows. And, like my question above, if they would be expected to fill on the first flood. These to me are interesting questions that help newbies like myself better understand how iAVs works.

I should also say that here in Costa Rica I have been to three quarries and more than a few aggregate retailers and have yet to find sand that is better than my current mix. I'm sure it's here somewhere, so I'll keep looking. But it ain't easy!

Cheers,
Jeff

Edited by JeffH (see edit history)

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Hi JH

1 hour ago, JeffH said:

Hi Mark,

not every combination/permutation has been tried. Those of us that come from a science background are interested in figuring out what kind of variations might work and have questions that, while obvious to you, arise because we haven't had the hands on experience with these types of systems.

Probably not every combination ? But scientific studies have been done on this, for more than 100 years.

So coming from a sciennce background I would thaught that looking in to former studies would be a first place to start ?

These to me are interesting questions that help newbies like myself better understand how iAVs works.

Don't know if you get a better understanding by reading the quote below?

I hope it can be of some help for you, the Q's you ask have been discussed in other threads as well

ICheers,
Jeff

cheers

 

 

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8 hours ago, Mark McMurtry said:

No offense intended to you or anyone else ... but I'm done attempting to define/explain sand and related performance criteria/variables..  I just do not know how to communicate in a manner that people can seemingly understand.  I'm SO very weary of this.  At times it appears to me the at least some if not most people just refuse to think and/or understand.  Not saying this is true in your case, yet I still do not know how to communicate.  I never had the slightest problem sourcing sand (in the US or in Africa).  Not claiming that everything I sourced 'worked' exactly the same ... I knew what was too fine an/or too course just by looking at it, playing with it in my hands, by making 'careful' observation.

I suggest that there is NO substitute for first-hand experience - while paying close attention to what 'behaves'/performs as desired and what does not.  Doing is learning and vice versa.  As I understand, you are aware that your media is far coarser than I've trialled.  Then how can it be any surprise that it does not behave/perform as desired?  Too fine won't drain well, too coarse won't saturate - duh.  This is SO basic/fundamental to me that I apparently can't seem to describe/explain it.  

I used/recommend what I've defined/described repeatedly every way I know.  The ATSM C-33 specification (US) 'worked' performed spectacularly for me.  This specification is used throughout the world (by different terms in various countries) to make structural quality concrete, whether in the US, Oz, China, Egypt or anywhere else.  It is not expensive or at all difficult to source - IMO.  It has clearly defined criteria such as NO carbonate or salts or silt and defined particle size distribution limits.  If you get material that meets this specification (not all vendors are competent, honest or knowledgeable but most who quarry for commercial contract work are) then it should work just fine - it always did for me.  I'm not claiming that it is the ideal - no one actually knows what the "ideal" is.  No one also knows what the limits are - how far one can deviate from what I tested/used and still achieve an adequate result - however defined. I know that I had absolutely NO problem whatever in sourcing or using sand that performed - more than adequately.  I obviously DO have a problem communicating.  

At this point, I'm SO sick of trying to 'define'/explain sand that I admittedly get angry (profound frustration)  just 'thinking' about it.  iAVs was 'about' people who needed a better/more reliable diet being able to accomplish/provide more security/vitality for themselves then they otherwise could in constrained circumstances/environments.  It is and never was about technology, equipment, hardware or devices - its biology and 'common sense' (which is obviously NOT common), and also not magic or woo-woo or 'technology'.  

I'll get off my soap-box now by concluding that it categorically amazes and shocks me that many if not most people seem to have grave difficulty understanding any of this (IMO in too many cases deliberately) and that at this juncture I feel it is now up to others to attempt to explain/describe the nuances since I am provably not able to do so.  I'm not suggesting that I want this to be the case, just that it is apparent - at least to me - that this is a fact.  How/why this is is open to conjecture and speculation - as is EVERYthing else wrt AP fantasyland IMO - is unfathomable to me.  

I fail to see how anyone could be offended by your heartfelt expression of frustration.  As someone who has, so closely, shared your AP journey of the past two years, I empathise with your situation.....and, as someone who stumbled on the correct sand at the first attempt, I've never understood the apparent difficulty that people have had in sourcing suitable sand.

With the benefit of hindsight, we may have contributed to the confusion surrounding sand by providing so much information about it....in response to suggestions that people had difficulty.  Your identification of the ASTM C-33 'construction sand' specification was probably all that we should have said about it.

Your gift to the world remains undiminished.....and I'm confident that it will assume its rightful place in the broader food production scheme of things.  My view is borne out by the growing number of start ups....and by the level of enquiry that is starting to happen.....ironically outside of the so-called 'developed' world.  I guess people are less inclined to want to tinker when they are hungry.

6 hours ago, JeffH said:

Hi Mark,I totally get your frustration. But remember that many of us are coming at this new and don't yet have the feel for the sand and its characteristics. The info you have on the iAVs website is fairly clear but it's also stated in several places that these are guidelines and not every combination/permutation has been tried. Those of us that come from a science background are interested in figuring out what kind of variations might work and have questions that, while obvious to you, arise because we haven't had the hands on experience with these types of systems.

Jeff....how (coming from a science background) will you know "what kind of variations might work" if you are unable to compare them with something.  It's entirely possible that you will get something to 'work' but how will you quantify its performance if you don't have a benchmark (a control) against which to measure it.

Having said that, I concede that it's everybody's entitlement to do what they want.....and to to accept the outcomes that they get....but it's our entitlement to say whether it's iAVs.....or not!

As a relative newcomer, you may be suprised by the apparent sensitivity that exists around iAVs.  It's likely that you will also not be aware of the fact that, while iAVs is the most widely researched (and most thoroughly documented) aquaponics variant, it (and its founder) has been subjected to a level of critical (in the obnoxious sense) scrutiny unparalled in the brief history of aquaponics.  None of the other variants.....including gravel culture....DWC....NFT....have been kicked around like iAVs - notwithstanding the fact that the best of them have yet to demonstrate that they have anything like the same productivity, resilience or sustainability as iAVs does.

None of this has anything to do with you on a personal level.  The irrational bullsh!t....and Mark's (and my) reaction to it...is just something you have to learn to cope with if you have anything to do with iAVs.

I'm not as battle-scarred as Mark.  I'm happy to continue to talk about sand (and why it's better) for the forseeable future.  

Gary

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BTW Jeff, You may or may not have a 'problem' with your sand selection.  First solve the 'problem' of no fish (no particulate 'wastes').  Its amazing (to me) just how fast feces (especially following mastication via a pump impeller) can clog anything deemed to be filter.  Microscopic particles lodge between surface sand grains (starting at the very bottom) and this facilitates lateral movement of the water down the length of the bed (when level).   I've always 'had' - and fed - the fish from day one - with at most an inoculation a few days prior to adding the fish by dosing Fritzyme 7 and ammonia.  From the first day (feeding), water went the length of the furrows (up to 6 m long) in mere minutes, then the furrows filled and water largely entered the sand laterally (into side slope of furrows).  What happens next (in/to the furrows) is a different chapter ...  BTW, this same longitudinal, then lateral water transport to crops also applies at vast scale, such as lettuce fields in AZ large enough to see the curvature of the Earth on the horizon.  

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I've waited for you - or anyone else - to acknowledge/respond to my 'comment' (suggestion) made on Wed. - either pro or con.   If/since/when people don't appreciate/want my input - okay - fine.   How anyone can 'think' that they're filtering fish wastes where there are not any fish (or feed) is 'beyond' my understanding.  As too is the vast majority of what has transpired here (and not) over the past 2.5 years.  

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Thanks Mark and Gary for your comments and suggestions. Gary, it has been somewhat of a surprise to me to read the tone of many of the comments here but it seems there is quite a history that, as a newcomer, I'm (perhaps fortunately!) not fully aware of. At any rate, I appreciate that you and Mark continue to provide feedback to newcomers like myself, despite the fact that much of what we ask and wonder about has been hashed over before. It's the nature of forums like these too that make communication difficult. Everyone comes at this with different experience and perspectives and reasons for trying to make fish and plants get along. 

Mark, yes, I'm definitely ready to get some fish and hope to have some by next week. I have just been waiting for water to clear of some silt that was left following my modest washing of the media before I added water. I didn't wash it very much because I wanted to leave a good percentage of smaller particles (since my "sand" was a bit large to start with). Over the past week though, the sand bed has been filtering this out so that the water is getting much clearer. I agree that the missing ingredient at this stage is some fish feces so I'm hoping to address this in the coming days.

By the way, the comments that you made in your Wed post are most helpful because they provide the kind of "rules of thumb" that you only get from experience. For me, it's very useful to know that the water flowed down the entire furrows from the start, for example. 

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Hi all,

Some updates today. I finally added some fish to my system! 20 Mojarra (I think Cryptoheros septemfasciatus) - a common river fish in Costa Rica that is hardy and easy to keep. The pH reading in my tank surprised me (I hadn't tested it for a while) - up around 8. I guess the my sand isn't as inert as I was hoping. However, the fish seem to be doing okay so far. I also added a common pleco (Hypostomus plecostomus) for algae control. And I've added some plants to my grow bed. A combination of cilantro, some sweet peppers, and some very sad tomato plants that I had been neglecting. It will be interesting to see if they can recover in the sand bed! Maybe I'll add a healthier one today as well for comparison. For added fun, I planted some seeds as well to see how they do.

 

 

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Jeff,

Thank you for your updates on this forum. Your questions and comments are thoughtful and helpful. Since i have not set up a sand bed yet i am living vicariously through your trials and tribulations.

Jens

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Hi Jens,

Thanks for your kind comments! I'm hoping over the next few months to build out something a little more substantial now that we have a small piece of land to work with. It's an incremental step as I slowly navigate how to start a small business here in Costa Rica. I'm still on the lookout for more suitable sand but am also planning on adding a raft system as well, especially for crops like lettuce, spinach, and arugula.

We have a notion of moving up your way (N. Cali) at some point in the (maybe distant!) future so it will be great to hear how your build goes! Are you planning on starting something in the near future?

Cheers,
Jeff

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My family and I moved to the country a few years ago. We are refurbishing a horse boarding operation and starting a small Almond orchard. These things are keeping me busy. It's ironic, I now have the space to do all kinds of things but no time. I really liked the simplicity of the non recirculating hydroponics. That is probably going to be my first related project. Someday i would like to try an iavs.

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8 hours ago, Jcnielsen4 said:

Someday i would like to try an iavs.

Hi Jen, Let's face it. "Someday" never comes.  Nothing happens.  I don't mean to be cruel.  "If you want to get something done, do it (now)."

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