mhaigh

Sand Bed Details

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Is the 10-12/kg/m3 considering all production or just the fish.  If not what needs to be figured  is the energy use per kg of food produced (fish and plant).   Refresh my memory, but have the numbers from the leap theorycrafting/discussion been proven to work consistently and be duplicated several times?

 

 I have had lots of great theories that when put into use were just not great. Not intending to be argumentative, just playing devil's advocate here.   . With greatly increased oxygenation in the bed plant growth should be(was reported to be) greater, BOD(biological oxygen demand) should be considerably lower in the water column due to greater atmospheric exchange with the greater surface area and dwell time.  The sand bed effectively removes a percentage oxygen consumption for bacterial conversion and plant use out of the  water column. The air pump. is likely redundant as his first trials did not have it.   I've seen how BOD increases as the system runs and was the primary reason to start removing solids in other type system/configuration.

 

For me it's a slap myself in the face and go "Why didn't I think of that".   The sheer genius in the simplicity of the design becomes more evident with each review.

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Vela,  let's continue discussion in your old leap thread so we don't derail this one further.  Some clarification/Insight to use of sand and dwell time in the sand bed is in the thread so I will leave them here as they might prove useful.

 

I put in the link to that thread for anyone wishing to follow it.

 

http://aquaponicsnation.com/forums/topic/6622-low-energy-aquaponics-leap/page-10?hl=leap

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Vela,  let's continue discussion in your old leap thread so we don't derail this one further.  Some clarification/Insight to use of sand and dwell time in the sand bed is in the thread so I will leave them here as they might prove useful.

 

I put in the link to that thread for anyone wishing to follow it.

 

http://aquaponicsnation.com/forums/topic/6622-low-energy-aquaponics-leap/page-10?hl=leap

Good idea. I'll post a reply over there.

Edited by velacreations (see edit history)

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For me it's a slap myself in the face and go "Why didn't I think of that".   The sheer genius in the simplicity of the design becomes more evident with each review.

I completely agree, and think there is great value in this design/concept. The mere improvement of surface area vs gravel would be enough to warrant significant change in the way most people approach F&D systems.

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Mark,

 

Did you ever trial root crops such as carrots in the sand bed.  This is one area that Gravel beds struggled with, but I would imagine would work just fine in a sand bed.

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Mark,

 

Did you ever trial root crops such as carrots in the sand bed.  This is one area that Gravel beds struggled with, but I would imagine would work just fine in a sand bed.

yes, in the original AP vs HP trials and the 86 pilot.. Also beet and radish.   Also chard, spinach, lettuces, beans, winged-bean and various peppers too.  Beans consistently did very VERY well, believe it or not.  (great food value)

Carrot did better in AP than HP but not as well as soil contrast in 86.  I imagine sand also better than gravel BUT the bulk density of sand is still too high for good radial expansion from root crops.  If you like short, narly carrots, fine!

Beet did better than carrot but not great,  Radish like carrot were mostly 'deformed' - still plenty edible, not good food value.

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Uncertain as to where the best place to post this is, so why not here:

 

 

[ splash splash, crunch crunch, snort snort ]
 
NOT a comprehensive survey by any means: more for my amusement if not your entertainment.
(I also have a database of other RAS as reported from mid-1970's thru 80's but these are not being compared below)
 
And before someone declares, "Apples and Oranges", this is more like "Mackerel and Mushrooms" ... 
 
First up, a few more or less random finds from Google search on "maximum tilapia yield per volume" and highly similar phrases (today)
 
UAZ 2008  Tilapia @ 0.44 lb/gal/yr,  55K gal raceway, flow thru at 500 l/min (=8,000 gph = 192K gpd, = 350% replacement per day) not Recirc. - in AZ - WTF?
tilapia to 244 g in 222 days  (iAVs R1 mean size achieved in <100 days)
up to 1.19 g/f/d   (iAVs 1.72 to 2.06 g/f/d in R1 ratio study means, not maximized or even 'pushed' )
55,000 gal x 3.5 x 365 = 70,262,500 gal/yr for 24,200 lb LW = 0.000342 lb/gal  CORECTION 0.000000342 lb/gal (3.43 e-7)
 
UAZ/Kuwait (no date, 90's?)  male tilapia @ 0.44 lb/gal/yr  (56.8 kg m-3 yr-1)  (per tank volume, not water consumption)  flow thru, not RAS - in Kuwait?  WTF?.  
partial discharge to GH Tomato in 'soil' media with <10% nutrient/water supplied from aqua discharge w/ mean yield @ 7.56 kg/plt  (desert sun).
55,000 gal tanks,  600 plants @ 2x/yr 24,200 lb tilapia, 20,000 lb tomato (type, grade?) from 1200 plants, both  fert. & irrig, water  dominantly NOT aqua sourced, 
H2O not returned to fish, soil drainage and majority tank discharge used to irrigate alfalfa  - cannot calculate biomass/volume from data provided
 
NCSU Fish Barn - multi-stage (stock split) RAS w/ 10% 'exchange' per day  (total tank volume approx 66,000 gal. as 6 tanks)
claimed mean 0.53 lb/gal/yr  or 63.4 kg m-3 yr-1   - density and other factors/variables not stated in 'report' (advertisement) viewed
maximum claim 0.66 lb/gal/yr or 79.26 kg m-3 yr-1  very high cost, very high energy
    66K gal + 10%/day = 66,000 + (6600 *365) = 2,475,000 gal ( 9,360 cu m)  for 124,228 lb LW = 0.05012 lb/gal   (no produce. HIGH cost)
DELETED misstated comparison 
http://www.ncagr.gov/markets/aquaculture/Tilapia01.pdf   I didn't study this 'report'  (bin dar dun dat)     
 
Noted: a LW tilapia price in NC (2001-2002) claimed at $1.40 lb.    (LOL = in your dreams, Tom!,  that is if your conscience can even get to sleep, assuming you have one)  
 aka, retail fillet would almost $8/lb or maybe more  ,< not even in 2014 in NC except maybe at a few Research Triangle area food boutiques.
 
random search result dated Aug 2013, stating US avg retail for 3 to 5 oz fresh tilapia fillet = $2.20 to $2.30 each - retail (also up more than 10% each of the prior 2 years)
2 @ 4 oz fillet per fish = 8 oz per LW fish  at 0.30 yield = 24 oz (680 g) LW fish, after processing and shipping costs and retail mark-up for $4.50 in 2013
IF at 1 kg LW and 0.35 yield > 2 ea @ 6 to 7 oz fillets (12.3 oz per fish).  At $.60 per oz retail (not grower, processor or wholesaler) = $7.40 per fish at retail
 
random ad:  25 lb of 6-8 oz tilapia filet from Java for $108, plus shipping and frozen I presume   50# for $393 delivered to me = $7.86/lb today (not a deal IMO)
 
Sigh.   So much poop, and so little time to scrap it off my boots.  .... [ clomp clomp squish squish plop plop ]
 
===========
 
UVI, Rakocy et al (last 'report', 'best')   no date - multiple cropping intervals and spp, co-mangled (sic) as (pseudo) results
Means:  per grow-out tank volume only = 67.5 kg m-3 yr-1    (stocking 50 to 80g 'fingerlings' (LOL), w/ up to 20% mortality, etc. etc. blah blah
per system volume = 19.4  kg m-3 yr-1 iAVs (R1 means below) - up to 120 kg m-3 yr-1 with optimal management
per annual volume = 2.84 (not including rain received)   iAVs  (R1 ratio study means) 7.7 to 8.9 kg m-3  w/ NO rain 
110 cu m + 731 cu m (+ rain, below) for 2106 kg    4644 lb / 222,169+ gal = 0.0209 lb/gal
BUT average annual rainfall in St Thomas is 45.01 inches (or 3.371 ft/yr, 1.03 m)    (per weather.com)
UVI Raft tank surface area (only) = 214 sq m or 2,303.5 sq ft
which is 8640 cubic ft of rain catchment or 64,632 US Gal or 244.6 cu meter PER YEAR (wholly unaccounted/unacknowledged, IMO fraudulent if alleged to be science)
SO, 110 cu m system + 731 cu m (acknowledged makeup) + 245 cu m of rain collected = 1086 cu m/yr    Therefor: 4644 lb /286,891 gal = 0.0162 lb/gal
 
===========
 
1988 McMurtry et al  iAVs ratio studies - explicitly NOT intended to demonstrate maximal productivity, or anywhere close (not the goal/purpose)
R1 means: 47 to 57 kg/m3/yr to 250 g   (at moderate-LOW stocking density, yield varied by v:v ratio)
@50 kg = 0.42 lb/gal  @ 55 kg = 0.46 lb/gal
 8.3 m3/yr per 1 cu m grow-out @ +2% /day  (w/ significant fraction marketable as plant biomass)
1.0 +(1 x0.02 x365) = 8.3 cu m  (  @ 55kg or 121 lb /2,192 gal = 0.0552 lb/gal ) 
- or 3.41 times more efficient water use (fish yield only) than UVI  , < deleted >
^^^ w/o St Thomas, USVI average rainfall included ^^^
 
1992-94 Mora et al (iAVs) reported  2@26,000 gal (197 m3)  and 50,000 lb/yr (22,780 kg/yr) = 115.634 kg m-3  = 0.96 lb/gal  ---- first lap in the pool, by a complete novice!
Make-up water volume not stated (would include fraction incorporated into aka sold as plant biomass), but less than 2% system volume per day (even less in winter)
55,000 + ((55,000 x.02) x 365)) = 456,500 gal/yr  for 50,000 lb LW or  0.1095 lb/gal -   or 6.76 times better efficacy than UVI (fish aspect only) ntm different plant products
GH was heated in winter but in-ground tanks were not.  Stock-split and/or dynamic stocking management techniques would undoubtedly result in even higher yields/volume.
 
[ Swirl Swirl Swish Swish Glug Glug ]
 
"Brought to you today by Luciner's Castor Oil Flakes, long in relief and short in the can ..."  Firesign Theater
 
 
edit to correct quote , and incorrect unit, and gross error , and ...
 
Edited by Mark McMurtry (see edit history)
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Thanks for the kind suggestion despite ineffectual result.  Escalating, ongoing ineffectiveness IMO.   My primary regret is failing to address any significant fraction of the true need I've witneessed, in turn but a glint off one wave in a seething rising sea.   My second regret is failing to counter exploding misconceptions however intended.  At the time Tom & Paula gained traction with gravel, I was overseas.  Once I learned of this 'development', I did attempt, more than once, to get them to switch to sand - or at least compare result - and some other suggestions as well - obviously sans impact.   IMO, the rest is 'history' and currently viewed as grotesque if not perverse relative to my aspiration.

 

"There's a fine line between genius and insanity ... so I erased it." - anon.

Hi Mark.

I think part of the problem that people went with gravel is the easy access. I live in Hawaii and here people use what we have an abundance of, lava rock.

I went browsing for course sand in the usual places and so far no luck. I know someone has it, it is just a matter of finding it.

Once I do, provided it s not too expensive, I plan on giving the sand GB a try. Thanks again for your research.

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I can fully concur on the "part of the problem' statement - albeit IMO that's the 'biggie' that basically generated at the others.

 

I've never been to Hawaii and have no idea what your local constraints or costs might be.  

OTOH, TMK anywhere that has the capability of making concrete - and in very many palces that do not - can access crushed quartz or granite sand by the mega-tonne -and  at least as readily as gravel (exception granted for driveways)).

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Sooo... I am correct in my presumption that I was (am) being baited.    Sorry (not really), your 'hook, line and sinker' action is of no relevance or consequence to me.  

My mother taught me well to never attempt to argue with someone who does not have a shared understanding of the words being deployed, be that of your (my) usage or theirs (yours).  We obviously have vastly divergent understandings of what constitutes science, experiment, proof, validity, efficacy, etc.  We come from and exist in entirely different 'worlds' (or so it would appear to me).   I understand that you have your felt compelling prejudices, as I too have mine.   If you want to bicker over what these are, please solicit someone else.   I've no interest in 'discussing' what I view as inappropriate (at best) to addressing global constraints or human needs.  I also maintain no illusion that I can or ever will positively influence anyone on anything- especially with adherents of the highly-fractious, evangelical religion of AP.  

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Why you think I am baiting you has me at a loss.
 
Simple question which I would think has a simple answer. 
 
I don't see it as an argument or a prejudice.  My understanding and practice of the science underpinning aquaculture is adequate enough to stay focused on the topic.  "Sand Bed Details".
 
My interest is in your experience experimenting with them, using sand, and if you found what the limiting factor/s is/are.
 
You have made many reference to the butchering of your work when changed to pea gravel, then onto other larger media such as hydroton.  
 
Surely there had to be a reason for the change by the "butchers" that was not driven by ignorance and stupidity as you imply.
 
In your experience, how long and at what feed load can the sand bed operate effectively for?

 

Further:

 

I've no interest in 'discussing' what I view as inappropriate (at best) to addressing global constraints or human needs.

 

We are "discussing" your sand beds, aren't we? 

Edited by Paul Van der Werf (see edit history)
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yes, I've no doubt at all that you 'just don't get it' - understand what I'm saying or inferring - about anything at all.  And I believe that I 'appreciate' why (how that is).

and TMK I never said "butchered" I said 'bastardized' - which is a historical fact (no one is asking you to accept, believe or especially like it)

and yes, first from willful ignorance, subsequently with serial stupidity and ultimately spread through gullibility at light speed

Absolute <blankity blank> never was my problem or responsibility,  so I'm not turning it into one now - for anyone.

So, congratulations Paul, you are now 'officially' on "ignore".  Say, 'think' (feel),  a do precisely what you want - since everyone does,   I could GAFF.

Holy art thou, sycophants to the Cult of St. James.  May all your seances be as pungent.

Sorely tempted to FLUSH this entire load ...      where's my guitar, ahhhh   Key of F sharp major.  Hit it Jimmy ...

 

edit typo

Edited by Mark McMurtry (see edit history)

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yes, I've no doubt at all that you 'just don't get it' - understand what I'm saying or inferring - about anything at all.  And I believe that I 'appreciate' why (how that is).

and TMK I never said "butchered" I said 'bastardized' - which is a historical fact (no one is asking you to accept, believe or especially like it)

and yes, first from willful ignorance, subsequently with serial stupidity and ultimately spread through gullibility at light speed

Absolute <blankity blank> never was my problem or responsibility,  so I'm not turning it into one now - for anyone.

So, congratulations Paul, you are nor 'officially' on "ignore".  Say, 'think' (feel),  a do precisely what you want - since everyone does,   I could GAFF.

Holy art thou, sycophants to the Cult of St. James.  May all your seances be as pugnant.

Sorely tempted to FLUSH this entire load ...      where's my guitar, ahhhh   Key of F sharp major.  Hit it Jimmy ...

 

Well Mark, you can't blame me for not "getting it" because of the loads of incoherent sh*t you dribble in the midst of your rambling insults.  Perhaps it is a way for you to leverage your "supreme intelligence" or you are deliberately misguiding the conversation because you simply don't have an answer.  That's is fine.  It would have been easier to understand if you had simply said (for us stupid and willfully ignorant), "I don't know."

 

It is a bit like comparing two methods with completely different crops and for the yields for crops you don't grow, state "should be good" as irrefutable "proof" your "science writ" is spiffy.  Makes for great story telling when you can just go on faith that gravity exists, milking cats is a business worth investigating and rocking horse sh*t has great potential.

 

I would ask though, if you are so hell bent every form of aquaponics, excluding your own, has no place in food production, than why the **** are you here?   To be honest, I am disappointed you chose this path with me as I was keen to learn and help shine some light on your work.  At this point, my opinion of you is diminished to the point of no return.

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Mark,

 

You have misinterpreted Pauls question wrt sand bed densities and longevity.  He has long advocated that oxygen limits and filtration limits should determine stocking densities rather than volume ratios of water such as 1 fish per 10 liters as was commonly used.  Paul and Gary have long strived to show this through the past several years and have taken rather a lot of abuse from other "aquaponic fundies"  who have preached the Gospel "all you need is rocks."

 

Paul is pretty straightforward and is not the kind to "trick" people.  He has risen the bar on this site at least on the value of calculations and measurements instead of success measured anecdotally. 

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I have been around this forum long enough to know the Moderators don't work like that Smatthew.

 

Anyway, taking aside that I am an ignorant evangelist and somewhat dim of wit, I think the loading capacity of the sand bed without pre filtration is a very important question.

 

Consider, media beds with larger void space and their limits with organic solid loading, sand, without prefiltration "should" have similar, if not less tolerance of organics.

 

I have experience in this and know people who have tried various types of media (including sand) in side by side trails in integrated aquaculture.  I prefer to hear directly from those that have worked with submerged packed sand filters.

 

Just today we cleaned out the two greenhouse and four large lined beds to start working on Mark's  method.  However, if the Mark is unable or not willing to tutor me in his method, I am not prepared to spend more time and money experimenting with it blind.

 

It is a shame.

Edited by Paul Van der Werf (see edit history)
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Not to step on any toes, here, but I agree that what Paul is asking is relevant, and I would also like to know.  In a practical sense, knowing how long a filtration media will work contributes a lot towards the decision of whether or not to use that media.  If something only works great for a short time, then it's best to know that upfront.  Most of the tests I have seen have been short duration (<6 months)

Edited by velacreations (see edit history)

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My two cents for what it is worth.  I know what I "fish" out of my RFF and it is no small amount each week.  I cannot imagine not having a filter of some sort working with any media. Why would sand be the exception?  It will clog the works.  I know it is eventually broken down by bacteria and all, but that would have to be sme really fast super bacteria to keep pace with the waste. Or not.  I guess I won't know till I try it.  Looking for sand in all the wrong places.... :)

Edited by GaryD
Removed provocative and unhelpful content (see edit history)

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There are some vast  differences in how the sand bed would function vs  a simple rock/gravel/hydroton based flood and drain system. I don't claim to know all of them, but some that come to my mind.

 

1. Vastly greater amount of surface area with sand vs other media. Greater surface area = faster solids breakdown and greater fish load.

 

2. Dwell time is significantly different and is one reason breakdown is faster and likely occurs outside the water column thus reducing bioload of water column if this is true.

 

3. If #2 is correct, then atmospheric gas exchange is exponentially greater to allow a magnitude greater chemical reactions including breakdown of the solids. 

 

4. I would expect solid accumulation to be at the upper layers on the sand bed, where as in gravel beds it is generally found to accumulate at the bottom of the bed.

 

Some of this is speculative guesses as I do not know for sure, having not tried the system out yet and measured to see if my guesses are correct. The pity is that Paul is one of the few people that would be able to fully test the system and report on it's progress.

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1. Vastly greater amount of surface area with sand vs other media. Greater surface area = faster solids breakdown and greater fish load.

 

2. Dwell time is significantly different and is one reason breakdown is faster and likely occurs outside the water column thus reducing bioload of water column if this is true.

 

3. If #2 is correct, then atmospheric gas exchange is exponentially greater to allow a magnitude greater chemical reactions including breakdown of the solids. 

 

4. I would expect solid accumulation to be at the upper layers on the sand bed, where as in gravel beds it is generally found to accumulate at the bottom of the bed.

 

Greater surface area .. and or retention time ...to provide nitrification.. hence potentially higher fish load.. I understand

 

But faster solids breakdown?... Why/how?

 

If #1 is in fact NOT correct.. in relation to solids (and that relates to Paul's perfectly reasonable question IMO).... then #3 would not only be incorrect... but actually negatively inclined

 

And from personal experience.. I don't believe #4 to necessarily be correct...

 

In fact (and I'll photograph it tomorrow)... I'm currently pulling down and cleaning a hydroton grow bed (previously heavily stocked system.. and long term tomato root growth)... that's been running "constant flood" for 2 years...

 

That shows most of the solids accumulation in the middle third of the media... and I've seen similar results in any "gravel bed" that I've decommissioned... probably even more so... ;)

Edited by RupertofOZ (see edit history)

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There are some vast differences in how the sand bed would function vs a simple rock/gravel/hydroton based flood and drain system. I don't claim to know all of them, but some that come to my mind.

1. Vastly greater amount of surface area with sand vs other media. Greater surface area = faster solids breakdown and greater fish load.

2. Dwell time is significantly different and is one reason breakdown is faster and likely occurs outside the water column thus reducing bioload of water column if this is true.

3. If #2 is correct, then atmospheric gas exchange is exponentially greater to allow a magnitude greater chemical reactions including breakdown of the solids.

4. I would expect solid accumulation to be at the upper layers on the sand bed, where as in gravel beds it is generally found to accumulate at the bottom of the bed.

Some of this is speculative guesses as I do not know for sure, having not tried the system out yet and measured to see if my guesses are correct. The pity is that Paul is one of the few people that would be able to fully test the system and report on it's progress.

I still do not understand how sand has greater surface area. I use lava rock which are basically rock sponges. I have had pump failure for 4 days and never knew it because the lava rock held the water so well that the plants showed no sign of distress. Maybe someone can better explain how sand grains have such large surface areas? Edited by Strider (see edit history)

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Maybe someone can better explain how sand grains have such large surface areas?

 

Because there's a quadzillion of them in any given volume... and little void space between them...

Edited by RupertofOZ (see edit history)

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I still do not understand how sand has greater surface area. I use lava rock which are basically rock sponges. I have had pump failure for 4 days and never knew it because the lava rock held the water so well that the plants showed no sign of distress. Maybe someone can better explain how sand grains have such large surface areas?

 

Hi Strider

Try this http://www.nippon-bel.co.jp/tech/seminar06_e.html or this  http://brightagrotech.com/biological-surface-area-in-aquaponics/

 

cheers

Edited by ande (see edit history)

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Hi Ravnis

 

 


Quote:

 

4. I would expect solid accumulation to be at the upper layers on the sand bed, where as in gravel beds it is generally found to accumulate at the bottom of the bed.

 

Some of this is speculative guesses as I do not know for sure, having not tried the system out yet and measured to see if my guesses are correct. The pity is that Paul is one of the few people that would be able to fully test the system and report on it's progress.

 

You are right and it is called http://en.wikipedia.org/wiki/Schmutzdecke it's often scraped off (the top layer) on  regular intervals and used as fertilizer or soil enricher  on the large slow sand biofilters

 

cheers

 

Edited by ande (see edit history)
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