GaryD

iAVs.info - the Integrated Aqua-Vegeculture System

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Just a few questions that have not been answered and portrays my concerns with the iAVS... I have read over the below questions more than several times and don't know how I could ask them any simpler.

 

I am as curious to how the questions will be answered as I am with the content of the answers... Just asking and watching.

 

 

1. Who are the current iAVS commercial practioners that have replicated the iAVS? If there are some, why not mention this on the website?

 

None that I'm aware of.   If/when we become aware of such operators, we'll certainly publicise their efforts…..assuming that they permit such promotion.

2. Who bought the Boone / Mora operation after the USDA grant money ended and is the pilot still in operation as a thriving business using the iAVS? If still thriving, why not mention this on the website?

 

I don't know who bought the Boone Mora operation….except that someone did.  To the best of my knowledge, the operation has ceased to exist.

3. What is done when the "fish tank" half of the iAVS must be significantly salted so to cure particular ailments without harming salt sensitive vegetables or fruits and done without sacrificing the iAVS fundamentals?

 

If we're talking about a closed loop backyard system, it would be treated no differently to any other closed loop system in such circumstances……the fish would be removed from the tank while undergoing treatment.    In their absence, organic nutrients could be used (in lieu of the fish waste) to feed the plants.

 

Most of my system designs have had the capacity to isolate and, aside from something like a desktop demonstration system, I would probably take the same approach for any iAVs that I built in the future.

 

As for larger systems, the answer is hypothetical since, to the best of my knowledge, no disease of the sort that would require salting (or treatment with other medication) was encountered.  This may have been good luck but was more likely due to the use of tilapia - a particularly robust species. 

 

I think that the design of iAVs for commercial situations would be very different to that proposed for most backyard or village situations.  Consideration of disease or infestation would obviously need to be taken account of in any commercial design…..along with any other risk factor associated with controlled environment agriculture.  I could propose design criteria but that would be hypothetical given that I don't have any intention of setting a commercial aquaponics system at this stage.

 

4. Has there been an occurrence of media borne ailments or other ailments during the iAVS research or the Boone/Mora pilot within the "vegaculture" section"? If there were ailment occurrences, how were these resolved without impacting fish health nor sand biofiltration capabilities? If there were not ailment occurrences, does the evidence suggest the iAVS avoids media borne ailments from occuring?

 

Boone Mora makes specific mention of an endemic tomato wilt disease but he didn't contract it.    I recall Mark referring to some disease but I'll have to email him for the details.  In any case, I think it could be safely assumed that iAVs would be subject to the same disease risks as any other protected cropping operation…..and would have to deal with them in the same way that other production strategies do.

 

As to any evidence that suggests that iAVs avoids media-borne ailments……..all I can say about that is that there are many microbiological complexities about which we have yet to learn.  Suffice to say, sand (and organic matter) is a far more complex ecological environment than gravel…..or water.  It would be inappropriate, however, for me to speculate as to the nature of those complexities…..and whether iAVs is more or less susceptible to disease as an intrinsic feature of its design.

5. When the occasion arises to use other sources of nutrients or supplements, how would this be done without impacting fish health? If there is no need for any supplementation for any crop, does the evidence suggest the iAVS avoids plant nutritional deficiencies from occuring for any crop?

 

During the various iAVs trials, five types of plants were grown and all of their nutritional requirements were met by the food provided to the fish.  I can't speculate as to  which other plants' needs would be met.  That could only be determined by matching the nutrient profile of the water and the nutritional requirement of the plants - and then by conducting growing trials.

6. Since commercial operations also entail adhering to business regulations.... Can you list examples of how the iAVS would comply to potential business regulations without breaking the iAVS fundamentals?

 

iAVs would no doubt be subject to the same regulations as any other controlled environment agriculture undertaking.   I don't know what business regulations apply in your area so I can't suggest how iAVS would deal with them.

 

7. Will you be including a Frequently Asked Questions section on the iAVS website?

 

Yes……and we'd appreciate any suggestions that you might have.

 

With reference to your opening remarks, no-one is deliberately trying to conceal the truth around anything.

 

I can only answer those things about which I have direct knowledge.  

 

I will often have to defer to Mark - he's the subject expert around iAVs.  

 

In the event that you don't get what you need, I can only suggest that you frame the question differently.  There may be some things about which neither Mark nor I know……and, in those situations, "I don't know is the appropriate answer" - whether it satisfies the person asking it or not.

 

It has to be said that there are many things to do with iAVs about which little is known.

 

 

Gary

Edited by Gary Donaldson (see edit history)
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Hi Charles,

 

With respect to your questions about plant diseases, Mark offers the following…..

 

"In the 86 'study' I purchased local sand and as it turns-out ALL North Carolina area soils, including sands, has 'loads' of several Pseudomonas spp., due to over 300 years of continuous tobacco cultivation in that region.  Since tomato is also Solanaceae spp, this pathogen effected the tomato crop (only) during that project.  

 

So, when I started the ratio studies, and we had the same sand source,  I took the rational precaution to sterilize the sand (fumigated with methyl bromide) in advance of said studies.  I/we did not re-sterilize between crops.  In the first tomato crop the cultivar we grew was susceptible to another bacterial wilt as introduced from an adjacent research facility, either airborne or via human traffic.  We chose the 2nd tomato cultivar from among those known to be resistant to bacterial wilts.  

 

No other pathogens 'appeared' - not that they couldn't with inadequate sanitation protocols applied.  

 

And BTW, most hydroponic operations across the world routinely encounter these and/or other crop specific pathogens, in some cases catastrophically. The most recent significant example of this I'm personally aware of being EuroFresh (400 acre HP tomato operation in AZ),  who filed for Chapter 11 twice in the past 3 years due to disease outbreaks - and last year they were bought-out by NatureSweet who does employ far more comprehensive/strict sanitary practices.  They too still have to scout for/battle diseases constantly.  None of them use sand (or other granular media) at all and sand has no particular affinity for disease causing pathogens or vice versa to my knowledge.  

 

Specific diseases effect specific crop species regardless of the growing method and/or media (if any) employed.  This is not limited to olericulture or to North America.  All plant species everywhere can/will encounter diseases specific to them. Commercial growers aggressively combat same ( if they're wise) with resistant cultivar selections when possible, strict sanitation protocols, and any/all other preventative measures where possible regardless of growing method employed."

 

On the matter of the number of "types" of plants, he says…..

 

"No such thing as "type" (my blooper) - 20 cultivars, 13 Species,  9 Genus, 7 Families, 3 or 4 Orders,  and 2 or 3 Classes (Clades)." (That'll teach me to wing it.)

 

Gary

Edited by Gary Donaldson (see edit history)
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To be honest.. I'm not even really sure what the actual definition of "scale-neutral in application" means.. or is intended to mean..

 

But to the latter point... while it's documented and acknowledged that Boone Mora and TIm Garrett created and managed a USDA-funded  iAVs Commercial Demonstration Project... which one could perhaps argue might be defined as a "moderate" scale... (I wouldn't)

 

There is nothing to suggest that it can be successfully scaled, or has been ever scaled to a "massively-scaled commercial enterprise"

 

 

I'm more than happy to accept that there's merit in looking at iAVs methodologies and applications.... but I think it's far too early to wrap them in too much "hyperbole"

 

We've all seen that done way to many times in aquaponics... especially in regards to commercial application ;)

I took it to mean that the methods and materials whatever they might be work at all scales equally. An example of a nonscalable system would be an aquaponic gravel based system. Sure you could build a commercial sized system with gravel beds but rafts or NFT work better at that scale and you can move plants around as they grow. I could hose out a dirty NFT unit faster than I could move tons of heavy gravel around when it comes time to clean too.

(I'm not making a claim one way or the other on the scalability of the system in question) 

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I took it to mean that the methods and materials whatever they might be work at all scales equally. An example of a nonscalable system would be an aquaponic gravel based system. Sure you could build a commercial sized system with gravel beds but rafts or NFT work better at that scale and you can move plants around as they grow. I could hose out a dirty NFT unit faster than I could move tons of heavy gravel around when it comes time to clean too.

 

A sand bed is still a media bed... sand is just really fine gravel.... ;)

 

And the price of the specific sized sand... would very probably exceed that of a lined DWC bed.... which basically the sand bed is... other than it's filled with sand rather than water.... :D

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A sand bed is still a media bed... sand is just really fine gravel.... ;)

 

And the price of the specific sized sand... would very probably exceed that of a lined DWC bed.... which basically the sand bed is... other than it's filled with sand rather than water.... :D

We have citrus groves here in FL that are just sand. I wonder if it would be more cost effective here than elsewhere.

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We have citrus groves here in FL that are just sand. I wonder if it would be more cost effective here than elsewhere.

 

Yeah but they're "run to waste"... not recirculating AP or hydro...

Edited by RupertofOZ (see edit history)

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A sand bed is still a media bed... sand is just really fine gravel.... ;)

 

And the price of the specific sized sand... would very probably exceed that of a lined DWC bed.... which basically the sand bed is... other than it's filled with sand rather than water.... :D

 

While that might be the case for UVI-style raft troughs, it would be less so for a larger installation…….and there are other benefits that attend the use of sand that would make its use more cost-effective when all factors are taken into account…..and particularly if you start to attach more realistic values to water.

 

When it comes to any comparison between sand and gravel, sand is the more effective media - in every respect.

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Yeah but they're "run to waste"... not recirculating AP or hydro...

I didn't mean to grow the trees with this method.  Just that we have many acres of sand already in place that could be moved a very short distance vs paying for sand to be shipped in.

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Hi,

 

We've put three new articles up on the iAVs site:

Jobney….you should find something amongst that lot to help you decide if your local sand fits the bill.

 

Gary

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Hi Jeremiah,

 

You're not in my debt......we all owe Mark thanks for his generosity.

 

I look forward to seeing how your beds pan out.

 

We'll be adding new material to the site every few days.....so stay in touch.

 

Gary

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I too really want to try this. But several advantages and disadvantages of sand beds comes to mind. Many were listed here already. Obviously sand beds would not share many of the advantages of dual loop systems that separate fish and plants. But due to the nature of sand, the advantage is the drainage, natural water filtration, and media area per sq ft. that allows for larger amounts of beneficial bacteria.

However, in a commercial type system scrapping the sand between crops seems like a daughnting task. But there is a considerable water savings over raft systems. But raft systems are easier to manage as crops are rotated in from the seedling stage to the intermediate and finally the mature plant. But how many tomato or cucumber crops are grown on rafts?

Fish maintanence advantage goes to the dual loop system in terms of ease. But sand gives great filtration so how likely is disease in that type system? It seems like a sand filter would reduce the chance of disease.

It looks as though there are advantages to all systems as there are disadvantages.

Edited by Strider (see edit history)

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I too really want to try this. But several advantages and disadvantages of sand beds comes to mind. Many were listed here already. Obviously sand beds would not share many of the advantages of dual loop systems that separate fish and plants. But due to the nature of sand, the advantage is the drainage, natural water filtration, and media area per sq ft. that allows for larger amounts of beneficial bacteria.

 

Given the central role of the sand in the system, it would not be useful to cut it out of the loop for general operating purposes……but, that's not to say that fish production can't be isolated from plant production in the event of a disease or infestation.

 

The benefits of using sand discriminate in favour of a closed loop design.  Some of the reasons for "decoupling" are far less relevant with the iAVs.

However, in a commercial type system scrapping the sand between crops seems like a daughnting task. But there is a considerable water savings over raft systems. But raft systems are easier to manage as crops are rotated in from the seedling stage to the intermediate and finally the mature plant. But how many tomato or cucumber crops are grown on rafts?

 

We don't know at this stage if/when the sand needs changing.  Let's assume the worst.  Modern commercial greenhouses are highly mechanised and the sand could come and go out of the greenhouse using the same infrastructure as is used for harvesting crops and cleaning out plant residues and other types of hydro media.   The difference between sand and other hydro media is that of disposal.  Where acres of rock wool (or Styrofoam rafts) presents an environmental challenge, the sand has become a value-added sandy loam and could be used on adjacent farmland or perhaps even sold……or it could be taken out of the greenhouse, washed to rid it of unwanted residues before replacing it in the greenhouse.

 

These are operational issues that are routinely dealt with in commercial greenhouses.

Fish maintanence advantage goes to the dual loop system in terms of ease. But sand gives great filtration so how likely is disease in that type system? It seems like a sand filter would reduce the chance of disease.

 

Again, it depends on the scale of the operation but what could be easier than iAVs where there are no filters to buy or clean.   What could be more cost effective to build or operate?  The filtration system is the growing media.  The water is pumped out of the fish tank and allowed to drain back into the fish tank….that's it!  This was the promise made by the basic flood and drain design - but never delivered on.

It looks as though there are advantages to all systems as there are disadvantages.

 

I agree in principle.  

 

The difference is that, at this stage, the disadvantages of iAVs are perceived rather than proven.  We think that the media may need to be changed…..but we don't know what the timeframe is.  

 

We know that there are nutritional benefits associated with decoupling raft systems since they already require regular dosing but our experiience of iAVs suggests that, for the crops that were trialled at least, no dosing/supplementation was necessary.

 

The big benefit of being able to be decouple is isolation of fish and plants.  That's a system design issue that would be very easy to factor into any commercial iAVs system.

 

And that's what we've consistently said around iAVs……more work needs to be done to demonstrate its efficacy across a wider range of circumstances…..and that's what we're pushing for.

 

Straight out of the box, iAVs is already a much better system for backyarders than the basic flood and drain system….period!   It even stacks up very well against the RAS model (with attached growing system) in that it costs far less to build…..once again for backyard use.

 

The main question that has to be resolved in my mind is whether it's a viable commercial model.

 

One of the things that we have never canvassed is the matter of organic certification. 

 

Currently, the barrier to organic certification for most aquaponics systems hinges on the use of non-soil media.  Notwithstanding the flexibility demonstrated by Oregon Tilth (who certified the Friendly Aquaponics system) most certifying agencies struggle with the idea of NFT troughs and even raft tanks.  iAVs doesn't have that problem.  Sand + organics = soil.

 

The income potential of organically-cerfified produce (which consistently sells in most markets at twice to three times the price of non-organic produce) could well be the tipping point in favour of iAVs……even in the face of (perceived) disadvantages of the iAVs model.

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Proven advantages appear to be plentiful. Yet, proven disadvantages are quite scarce, if even that.

 

Are there any disadvantages at all that are proven rather than "perceived" for either the backyard hobbyist or commercial operators?

Edited by crsublette (see edit history)

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Proven advantages appear to be plentiful. Yet, proven disadvantages are quite scarce, if even that.

 

Are there any disadvantages at all that are proven rather than "perceived" for either the backyard hobbyist or commercial operators?

 

 

Yes. I could of swore I read where Mark stated that the sand had to be scraped after every crop. On a commercial scale that is an enormous amount of sand removal and change.  Just because it is something that commercial growers are geared up to do does not change the labor involved. 

I saw a large system (hydroponic) that was modular and easy to change out the grow media between tomato crops.  Remove one bag, insert the new bag w/ tomato plant.  That is what the sand system lacks...

Edited by Strider (see edit history)
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I may add that although I am inclined to agree that sand does indeed sound like a perfect media/filter I would also point out that it has not sprung up as the commercial standard to which other type systems are compared.  So I wonder why not?  As with all things, the proof is in the putting.....

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Well I wonder why can't sand be used in a dual loop type system?  Are the solids that get pumped into the sand bed at the very front that important. isn't it true that most of the solids will accumulate near the point of entry and be filtered out by the sand as the water runs down the trough? 
 

 

 

The benefits of using sand discriminate in favour of a closed loop design.  Some of the reasons for "decoupling" are far less relevant with the iAVs.

 

Are they?  Separate Ph control is always relevant regardless of the media type is it not? I cannot think of a single disadvantage separating the loops, even using sand. A good experiment would be using sand beds, one as Mark has done, and one in a dual loop system and see how the plants react. I would be willing to bet that there would be no or little difference.

 

We don't know at this stage if/when the sand needs changing.  Let's assume the worst.  Modern commercial greenhouses are highly mechanised and the sand could come and go out of the greenhouse using the same infrastructure as is used for harvesting crops and cleaning out plant residues and other types of hydro media.   The difference between sand and other hydro media is that of disposal.  Where acres of rock wool (or Styrofoam rafts) presents an environmental challenge, the sand has become a value-added sandy loam and could be used on adjacent farmland or perhaps even sold……or it could be taken out of the greenhouse, washed to rid it of unwanted residues before replacing it in the greenhouse.

These are operational issues that are routinely dealt with in commercial greenhouses.

 

It seems to me that if sand is not changed after every crop the water flow mechanics will be very different from the first crop. After sufficient build up on the surface of minerals and waste and algae, less water will flow down through the sand along the trough.  This could significantly change the characteristics of the sand bed, no?

 

Again, it depends on the scale of the operation but what could be easier than iAVs where there are no filters to buy or clean.   What could be more cost effective to build or operate?  The filtration system is the growing media.  The water is pumped out of the fish tank and allowed to drain back into the fish tank….that's it!  This was the promise made by the basic flood and drain design - but never delivered on.

Yes, I do like that about sand bed/filter systems.

 

The difference is that, at this stage, the disadvantages of iAVs are perceived rather than proven.  We think that the media may need to be changed…..but we don't know what the timeframe is.  

 

We know that there are nutritional benefits associated with decoupling raft systems since they already require regular dosing but our experiience of iAVs suggests that, for the crops that were trialled at least, no dosing/supplementation was necessary.

 

The big benefit of being able to be decouple is isolation of fish and plants.  That's a system design issue that would be very easy to factor into any commercial iAVs system.

 

And that's what we've consistently said around iAVs……more work needs to be done to demonstrate its efficacy across a wider range of circumstances…..and that's what we're pushing for.

 

Straight out of the box, iAVs is already a much better system for backyarders than the basic flood and drain system….period!   It even stacks up very well against the RAS model (with attached growing system) in that it costs far less to build…..once again for backyard use.

 

The main question that has to be resolved in my mind is whether it's a viable commercial model.

 

One of the things that we have never canvassed is the matter of organic certification. 

 

Currently, the barrier to organic certification for most aquaponics systems hinges on the use of non-soil media.  Notwithstanding the flexibility demonstrated by Oregon Tilth (who certified the Friendly Aquaponics system) most certifying agencies struggle with the idea of NFT troughs and even raft tanks.  iAVs doesn't have that problem.  Sand + organics = soil.

 

Yes, I went to a Hawaii Dept of Agriculture (HDOA) meeting where many guest speakers were invited to talk about Aquaponics in Hawaii. The representative from the HDOA got up and started suggesting that aquaponics growers should use UV lighting to sterilize their water. Well as you can imagine there was quite an uproar from the crowd and this poor guy got an ear full about UV killing beneficial bacteria and some yelling for him to get off the stage because he did not know what he was talking about.  There is a lot of misconception even in the official regulating agencies about what aquaponics entails and how it works.

 

The income potential of organically-cerfified produce (which consistently sells in most markets at twice to three times the price of non-organic produce) could well be the tipping point in favour of iAVs……even in the face of (perceived) disadvantages of the iAVs model.

 

Well that is why we are here, to figure out what is the potential for iAVs...  and then maybe getting the commercial community to adopt it?  For my part, I plan on building two beds, one in the dual loop as a separate loop, and one directly from the FT to the sand bed and back.  That should make it interesting.

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A sand bed is still a media bed... sand is just really fine gravel.... ;)

 

And the price of the specific sized sand... would very probably exceed that of a lined DWC bed.... which basically the sand bed is... other than it's filled with sand rather than water.... :D

Well yeah, but the real fine gravel (sand) is exactly what makes it so good. The surface area is exponentially greater, as is the filtering ability.

Edited by Strider (see edit history)

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I think I'm going to run mine with a constant flow of water trickling through the sand but never flooded.  Things I'm curious to see the implications of, compared to DWC:

  • Increased oxygen availability to roots
  • Increased (vertical) water velocity across roots
  • Very little solids accumulation on roots (filtered near surface)

My anecdotal experience with spinach is that I get more pythium in DWC than media beds.  I suspect it's oxygen availability, but that's just a guess.  I'm curious to see how sand beds are with regard to pythium.

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Yes. I could of swore I read where Mark stated that the sand had to be scraped after every crop. On a commercial scale that is an enormous amount of sand removal and change.  Just because it is something that commercial growers are geared up to do does not change the labor involved. 

I saw a large system (hydroponic) that was modular and easy to change out the grow media between tomato crops.  Remove one bag, insert the new bag w/ tomato plant.  That is what the sand system lacks...

 

Hi Jim,

 

For the record.....Mark never removed any sand during the life of any of his iAVs trial......nor did it happen with the commercial trials.  

 

Between crops, algae grew in furrows and sand surface.   In normal circumstances, the alga persisted only until the plants grew large enough to shade out the surface of the sand and then it would die off and eventually become part of the nutrient cycle.  

 

At one stage, Mark wanted to gauge the effects of running the system without plants.....to see what would happen.  In the absence of the plants, the algae continued to build up to the point where it hindered drainage of the water from the beds..

 

The remedy was to simply "disturb"  the alga mat in the bottom of furrows to permit percolation.  This took maybe 15-20 minutes for all 16 beds.   He did this about once a week for 2 - 3 weeks.  By then, the oncoming crop was sharing the surface and the remaining alga died back once again.

 

"Disturbing" the surface meant dragging a stick along the bottom of the sand furrows  which proved sufficient to allow the water to drain again.

 

I think I'm going to run mine with a constant flow of water trickling through the sand but never flooded.  Things I'm curious to see the implications of, compared to DWC:

  • Increased oxygen availability to roots
  • Increased (vertical) water velocity across roots
  • Very little solids accumulation on roots (filtered near surface)

My anecdotal experience with spinach is that I get more pythium in DWC than media beds.  I suspect it's oxygen availability, but that's just a guess.  I'm curious to see how sand beds are with regard to pythium.

 

Jeremiah,

 

If you alter the "flood and drain" cycle, you will not achieve the things that you've suggested.  The best way to effect aeration and filtration is to allow the furrows to fill with water....and then, over the ensuing couple of hours, to drain.  The act of filling the system with water.....and then draining it completely has the effect of drawing air down through the media.....for more complete gaseous exchange.

 

A constant flow will not achieve the same level of aeration.....nor the same level of nitrification activity......as the flood and drain prescription.

 

Gary

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Hi Jim,

 

For the record.....Mark never removed any sand during the life of any of his iAVs trial......nor did it happen with the commercial trials.  

 

Between crops, algae grew in furrows and sand surface.   In normal circumstances, the alga persisted only until the plants grew large enough to shade out the surface of the sand and then it would die off and eventually become part of the nutrient cycle.  

 

At one stage, Mark wanted to gauge the effects of running the system without plants.....to see what would happen.  In the absence of the plants, the algae continued to build up to the point where it hindered drainage of the water from the beds..

 

The remedy was to simply "disturb"  the alga mat in the bottom of furrows to permit percolation.  This took maybe 15-20 minutes for all 16 beds.   He did this about once a week for 2 - 3 weeks.  By then, the oncoming crop was sharing the surface and the remaining alga died back once again.

 

"Disturbing" the surface meant dragging a stick along the bottom of the sand furrows  which proved sufficient to allow the water to drain again.

 

 

 

I read something where he said he had to "scrap" the tops of the sand beds. I will try to find it.  Also, the algae that grows at my house can and does grow in the shade as well as the full sun. I have a water feature in full shade that I continuously have to clean due to algae buildup and there are no nutrients injected. 

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I think you'll find that whoever wrote that.....and it may have been me.....meant "scrape" (rather than "scrap").  In any case, "disturb" is a more accurate description of what he did.

 

Also, this "disturbing" thing only happens with the iAVs in the circumstances that I described.

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