Aeroponic design guideline roundup


#1

Introduction

This is a meta-post intended to organize useful information about designing aeroponic systems. It began with @Webb.Peter asking me to make an outline of topics and then fill in the blanks drawing on links and other suggestions he gave me as a starting point. At the time I’m writing this sentence, that’s been going on for over a week. I’m expecting this post will continue to evolve for some time.

Reference Designs

Discussion, pictures, video, etc. for systems people have built and grown plants with

Speculative Designs

These are ideas people have talked about, but so far we don’t have reports on example implementations

Understanding Nozzles and Droplet Behavior

Resources for understanding how atomizing nozzles work and how to select for desired spray pattern and droplet size. These sources are mostly about agricultural spraying.

  1. Terminology and units: These sources explain units and terms that are used for discussing droplet size in the context of agricultural spraying (pesticides, etc.). We’re interested in delivering nutrients to roots as opposed to killing stuff with pesticide, but the point is about understanding the physics around how small liquid droplets behave based on their size.

  2. Nozzles: Selection and Sizing (Virginia Cooperative Extension pdf) Abstract: “This fact sheet covers nozzle description, recommended use for common nozzle types, and orifce sizing for agricultural and turf sprayers. Proper selection of a nozzle type and size is essential for correct and accurate pesticide application. The nozzle is a major factor in determining the amount of spray applied to an area, uniformity of application, coverage obtained on the target surface, and amount of potential drift.”

  3. Plumbing Systems of Agricultural Sprayers (Virginia Cooperative Extension pdf) This talks about pumps, valves, hoses, flow rates, filters and strainers, etc.

Nutrient Formulas

  1. @atom’s Strawberry formula: Building aeroponic system and full automation (comment 23). Also see comment 25 from the same thread that explains more about the numbers from the strawberry formula comment.

  2. @atom’s lettuce formula: Building aeroponic system and full automation (comment 27)

Leafy Greens

  1. What do we know about root behavior of leafy greens in aeroponic conditions?

    • lettuce roots 9" tall by 7" wide: atom said, “I grow lettuce in the towers as its more efficient, the roots take up all the drop to the site below which is around 9” and widthwise they fill in the open space on the inner wall of the tower which equates to 7" per plant but its not the same inverted cone shape you get with a flat chamber due to the vertical aspect, its more of an elipse, wider than it is deep." [Source: this post]
  2. How can we plan for a good interaction between nozzles, roots, and the root chamber? What do we know about reasonable design goals for maintaining a good dispersion and circulation of nutrient droplets in the root chamber? How can the goodness of a proposed approach to misting be evaluated or quantified? What do we know about factors that should be included in the design of a root chamber? What do we know about selecting and placing appropriate nozzles?

    • max of 1mL nutrients per 100L root chamber; 5-80 micron droplets: atom said, “Ideally, the misting system should deliver no more than 1ml of liquid per 100L of root chamber volume, The mist should consist of 5-80 micron droplets and be directed into open space to prevent localised root wetting and uneven mist coverage.” [Source: this post]

    • root shape as a measurement of goodness: atom said, “Keep the roots too wet and you`ll notice they will head straight for the floor and pile up… If you keep them too dry (or the droplet size is too small) they will spread horizontally at the top of the chamber and form a canopy. This usually results in the roots under the canopy blocking mist to the top of the canopy. The goal is to create an inverted cone of roots that gains in both girth and length.” [Source: this post]

    • spray mist into the air–not onto something solid that it will stick to: atom said, “You may get away with a slightly shallower chamber for lettuce but a lot will depend on the nozzle type (mist pattern,cone diamter and throw distance) and placement. If you use netpots they will also reduce the available height.in the chamber The important thing is to ensure the mist coverage isnt restricted, upward firing nozzles in a low height chamber will tend to impact directly on the underside of the lid and droplets dont bounce” [Source this post]

  3. What do we know about preparing an appropriate aeroponic nutrient solution for leafy greens?

    • drain to waste advantages: atom recommends drain to waste because it reduces the potential for contamination, clean nutrients are less likely to clog nozzles, and the pH and nutrient content don’t need adjustments after the initial solution is prepared. [Source: this post]

    • 1/4 to 1/2 strength compared to hydroponic: atom said, “I always run 1/4 to 1/2 normal strength and fine tune based on the difference between the inlet and outlet ppm. For lettuce typically 100-250ppm (EC 0.2- 0.5) depending on the size… If you run high strength nutes and minimal water youll soon run into issues because there isnt much run off to take away the excess. When you run hpa youll discover plants want a lot less water than you thought possible…When you get the system up and running itll all fall into place unless you overdo the mist” [Source: this post]

  4. What do we know about methods of atomizing nutrient solution?

    • Pressure atomization: High pressure fluid comes out of a small opening forming a stream or sheet that breaks up into a spray of small particles. [Source: Grayco training pdf on atomization]

    • Air atomization: Blowing high pressure air jets at a low pressure stream of fluid breaks the fluid up into a spray. [Source: Grayco training pdf on atomization]

    • Centrifugal atomization: Fluid added to the center of a spinning disk gets accelerated by centrifugal force and flies off the edge of the disk as a sheet or ligaments of fluid that break up into a spray. [Source: Grayco training pdf on atomization]

    • High RPM spinning disks can be loud and hard to control [Source: atom’s comment]

  5. What do we know about implementing a control feedback loop for misting? How can we sense when to add more mist? What are good ways to decide how much mist to add? How do we sense if a nozzle is clogged?

  6. What do we know about validating the overall quality and effectiveness of an aeroponic design? How can we make good tests to understand whether prototype misting systems are garbage, mediocre, great, or whatever?

Process & General Notes

Comments, suggestions, corrections, etc. are welcome.


Building aeroponic system and full automation
Building aeroponic system and full automation
My shot at a "Food SuperComputer"
Syringe Pumps - Peristaltic Dosing Substitute & DIY Aeroponics
Choosing appropriate nozzles, pump or other related components for High Pressure Aeroponics
Which is the fastest method for growing crops
Vertical Farming Documentary
Aeroponic System Categorization (flex/vertical/horizontal trays)
Experimenting with fogponics, could you help?
#2

@Webb.Peter, In the atomization techniques category, this is interesting: https://google.com/patents/EP0052264B1

It’s the expired patent for the Ein-Gedi design that’s used in the General Hydroponics Rainforest. Instead of atomizing with a spraying nozzle, it uses centrifugal atomization with a spinning disk. I found some stuff on atomizing paint which talks about centrifugal atomization methods: http://wwwd.graco.com/training/concept_and_theory/Atomization%20v2.pdf


#3

So interesting! I’ve yet to hear of this method - although it makes perfect sense.

Check out the discussion here - I think until otherwise disproven “fogponics” fits in this category. If nothing else let’s get to the bottom of its application @Juan1 has done a great job documenting his experimentation so far. Check out one of our discussions here (I also link to a 1999 patent by secretary of agriculture for U.S. government on ultrasonic foggers for aeroponics).


#4

@Webb.Peter This looks really interesting, especially because you could control droplet size depending on disk speed. I have never seen a design like that tho, I wonder what the spraying area is comparable to a hpa misters.
I believe you are missing fogponic systems in your atomization discussion. I did not have a lot of success with it but I still believe it has great potential. Its a very sensible system, but it has advantages over aeroponics, like having fewer points of failure.

I have been thinking lately about gel nutrient solutions that would allow the plant to fully grow in that solution and be transported live easily. Something like a SAP (super absorbent polymer). Doing some research I came across this company in Japan, Mebiol, has developed a technology where roots are grown between two films of a plastic material. Check it out it’s pretty interesting.


#5

Oh boy - I’m glad you mentioned this! I’ve heard it brought up too many times to not learn more thanks for the TED talk! @drewthomas89 brought up gel’s to me just the other day, NASA I think has tried it, and I know is experimenting now with other slow release methods (I know Scotts makes products like that. The reason I bring it up because to me an important question I’ve had was How should a nutrient recipe change over time to best suit a plants current needs? What I mean is, can we just spray water for 4 hours and nutrient for another 4? Perhaps this is also impacted by light-cycle? @Jlniemi just brought this up in his thread here: Flushing strawberry.

I just had a conversation with @jimbell about nutrients as well. He’s working on trying to compile information for us to use to create aeroponic nutrient recipes for lettuce, and strawberries by pooling academic journal recommendations for plants and then trying to find commercial substitutes so we can replicate. If there’s any plant scientists or nutrient experts out there, even just experienced growers please start a thread about “the perfect nutrient recipe” for any type of plant - and how you got there.

One thing @Atom (as well as some of the major commercial companies I’ve heard talk about aero) has always repeated and people (myself included) have failed to listen to is that aeroponics’s biggest opportunity is control. To me, that is what a gel would lack, unless it were able to be perfectly designed to give the plant what was needed as its roots developed. If indeed this is what is being done - then it seems we are pursuing similar goals. I’d love to see a post devoted to “the perfect medium” with more information on gel’s - are you able to get your hands on anything you can test? Perhaps this is naive and unrelated - but as a kid I remember adding water absorbant pellets to soil. I’m curious what those were, maybe it’s totally irrelevant - I’m always interested in the “how do I get started” and too often replicating results isn’t possible, limiting impact.


Flushing strawberry - BRIX Content
#6

I`ve experimented with rotary disc atomisers (CDA).the main issues are the noise (10k+ rpm) and lack of control.


#7

Regarding the primary goal of this thread, I’m currently waiting on parts to arrive this week to finish my aeroponic build. It will be pretty basic to start with, and draw loosely on the guide from Sustainable Green Plants website. I’ll update with pictures and a BOM when it’s complete. I have a small personal budget allocated to this project for any improvements this group is able to advise. Here is the website mentioned:

http://sustainablegreenplants.com/


#8

@drewthomas89 I added links under the new “reference designs” heading in the original post.


#9

I would be wary of employing single use PET bottles as 110psi accumulators :wink: The compressed air isnt seperated from the nutrient by a physical barrier (butyl diaphragm or bladder). Solubility increases with pressure and the PH can be affected by anything dissolved in the solution.


#10

Thanks @Atom! No worries though, that’s one of the parts of the setup I’m changing. I have the accumulator that @Webb.Peter bought initially. I got the first round of shipments in today, and figured out what I’m missing for round 2.


#11

@Webb.Peter I stumbled across some interesting stuff from the Virginia Cooperative Extension, so I added a section on nozzles.


#12

Update: I’ve got the initial build together, and did a pressure test all night last night successfully. I’ve got a couple obvious modifications to make, and then I’ll get some pictures and a BOM up.

@wsnook Wow, this post has really grown since the last time I checked it; impressive


#13

Rough BOM for my version 1. There are a couple things I’m going to rework, and I’ll update the BOM, just wanted to get one out there. It does work great so far!


$300 Food Computer - MVP
Food Computer V2 working with Hydro- or Aeroponic system?
#14

@wsnook Could you add this post of videos to the section about existing systems?

Also, could include links to the pics I took of the V1 Food Server HPA system?

https://drive.google.com/open?id=0Bxo_YC67jiAEcnItemhjalF2SEk

Thanks.


#15

Done. I’m a bit fuzzy on the timeline and details for the v1 Food Server. I wrote a summary that I think is probably accurate. But, I’d appreciate if you look it over and let me know if I’m omitting or mis-representing anything important. In particular, if there’s a written description of the system someplace, it would be great to have a link.


#16

No, it really isn’t documented anywhere. I also never got to see the thing in use. I do know that it was built by Chad Sykes (very active on LinkedIn) who runs Indoor Harvest. We are working on a 4x8 sized aero system in STL that will be modeled very similar to this.

I took it apart December 2016. I’m pretty sure the systems will show up at Bates eventually, but that’s pure speculation.