Lost in the mist, or Twisted journeys in the AAA world (strawberry version)

Indoor Growing Hydroponics
122

Its hard for me to judge your hang times via the videos. I cant really judge how dense your mist is. They all look very similar. I think maybe once you get the flow rates calculated, that may help.

I like the way the alternate firing looks in your videos. Do you think thats helping with the mist uniformity? My roots seem to be liking the variable timing by having one nozzle with a second or two shorter OFF time than the other one.

As far as measuring the mist density, we might be able to use a light meter on one side of the chamber and light source on the other to measure the relative mist density, but Im not sure how useful that would be. My numbers would never correspond to your numbers, but I guess we could measure when the light level changed by 50% or something.

Something else occurred to me a few weeks ago about this whole NASA recommended droplet size range, and how that relates to us judging hang time.

NASA did those tests in orbit - I think. However, I have not been able to find any actual information on that or exactly how and where they did the experiments. Everyone on the forums says they were done in orbit, but I cant confirm that with any official documents.

IF they did do those experiments in orbit, that means there was ZERO GRAVITY!!!

Therefore, hang time does not apply, because the droplets would never fall! In the NASA experiments, every size of droplet would hang forever.

For us, there is no way we can keep 50uM droplets floating around. Even the 20 uM droplets fall pretty fast - 25 seconds/ft.

I keep going back to Atomizers video you linked to above. He has 90 seconds of OFF time between cycles, and the mist density doesnt drop that much the whole time. That tells me he is actually generating a ton of very fine droplets - 10 micron and smaller. More importantly, it looks to me like its those very fine droplets he is using to set his cycle rate on - not the larger droplets which will all be long gone anyway.

In other words, he isnt really using the 20-80 uM size range at all. It seems to me his droplets are skewed to a significantly smaller size range than he has been telling everyone.

What Im leading up to here is that our earlier conversation about limiting the hang time to what we would see with 20uM droplets might be a mistake. Doing that might be generating droplets that are too large on average.

The question is - how do we know which is correct? I would love to chat with Atomizer about this, but he will never talk to me again. Plus, I still wonder about some of the things he has said. I would have more confidence if he had posted more close up root pics with fuzzy hairs as well as some wider shots of good sized root balls. For all we can tell, Im growing better roots than he does.

I suspect we are going to have continue to experiment and let the roots tell us.

1 Like
123

I will return soon, but in meanwhile a little 0.2 second misting pulse video in slow mo. Nothing informative, just for fun. The first clang is the main solenoid valve opens, and then in real 500 ms the nozzle solenoids open and fire a short misting pulse.

1 Like
124

LOL I like that!

What I notice is your water solenoid is closing a few ms after the air solenoid - resulting in some run on flow. Doesnt look like a lot though.

Other than that, the mist pattern and quality look really good - especially for that short an ON time.

1 Like
125

Yeah, this is the problem I’m talking about almost from the beginning. Seems that it is not a solenoid problem because it is the same with different controllers, different solenoids places and even different solenoids themselves: I can’t install solenoid closer to the end because they are already at the nozzle :slight_smile: But still the same thing. Don’t know what else can I do with it.

image
image1343×1007 101 KB

The only thing left is a plastic disk between a nozzle base and caps: a nozzle has a special insert with a few holes that splits water and air. May be this insert is not rigid enough and after pressure stops just returns to its normal shape.

1 Like
126

I wonder if you could adjust for that if you used an additional timer on the water side? You could have it shut off a few ms sooner?

Another thought - is that solenoid a plunger type valve or a flap type or? Do you know the internal mechanics? Im wondering if the solenoid is having to push a volume of water out when it closes? Water is harder to move than air and it could just be it takes longer to move that water out of the way so it can close.

1 Like
127

I believe it would complicate the system a lot. I already have at least 3 relays to control (main valve and two nozzles), in case of different relays per solenoid I’ll have at least 5 relays, not mentioning controller pins, wires, SSR relay cost etc :slight_smile:

And honestly I believe it wouldn’t give any positive addition as water doesn’t have enough pressure to form required quality mist anymore. What do you think?

I would start with that insert but don’t know yet what to use instead.

If I correctly understand the difference the solenoids are plunger type ones: with an inner cylinder. But I think there is too much water to think this way… :thinking:

1 Like
128

Just thought I’d drop a message here to say Hi. I’m following this build too as I do research for my own builds because one of the plants I want to play with is strawberries. I’ll probably do my initial experiments with a lettuce for the fast grow times so I can run more trials in less time. Finding a lot of interesting things I haven’t seen mentioned here yet. Going to try and document it all and probably buy some parts to experiment with. Unfortunately the used laser diffraction machine i found that could very accurately measure droplet size in these experiments is like… $15,000 - $40,000 and I’m pretty sure I would end up homeless if I bought one.

I might see if I can find one at any of the universities near me and sign up to audit some class or something to get access to one… but i’ll need the equipment to test first.

2 Likes
129

Hi! Glad to see you in this thread!

Yes, this is real pain: it very hard to evaluate this parameter. “Mature” options cost too much, and homebrew ones can’t give enough resolution\be strong enough to trust their values.

Please share your findings with us. It is very interesting topic and we here have a lot of gaps.

Actually the major question is this 50 micron idea roots. I wasn’t able to find that NASA research almost everybody refers to.

1 Like
130

Thats something I find really odd. As far as I know, most NASA research - other than military crap - is open to anyone, so why is it so well hidden? Plus, I would think this information would be valuable and of interest to commercial growers as well as home growers.

Did it somehow get put under a patent or some sort of commercial agreement not to publish it?
I keep meaning to write tot someone at NASA and ask about it but I never seem to get it done.

1 Like
131

I forgot about this reference:

In the late 1990’s, NASA began examining Aeroponics as a possible means of actually growing food in space. In 1996, NASA began funding the research of Richard Stoner, the man who first patented the microchip that initially made the automatic watering of aeroponically grown plants possible. At the time, he was working on a way to grow plants aeroponically without using pesticides that are sometimes necessary to control pathogens through using liquid biocontrol. A year later, NASA was performing their own experiments for biocontrol. Experiments were conducted on growth chambers on the MIR Space Station, the Kennedy Space Center, and Colorado State University.

In 1998, Stoner began using NASA funding to develop an Aeroponics system that could be used effectively in space. In zero gravity, there were no sufficient ways to provide plants with moisture and nutrition. Additionally, it is also difficult to grow food in space because there is often very little room to keep water, fertilizer, media and other necessary supplies. Stoner was able to demonstrate that aeroponics is a viable way to overcome these obstacles and grow healthy vegetables aboard a spacecraft. Since aeroponics makes extremely efficient use of water, very little has to be used and stored. And since aeroponics requires no growing medium, none needs to be taken on space missions.

In 1999, Stoner, again using funding from NASA, developed an inflatable aeroponic growing system that could be used to efficiently grow food either on Earth or space. The system in completely self-contained, and the inflatability of the unit means that it can easily be deflated and stored in a small space when not in use.

It sounds like we need to look up this Stoner guy.

EDIT: Check out this link. This is more info than I have found anywhere else. Unfortunately, its still not the original source info, and several JPG files - pics of roots, etc - seem to be missing. Still lots of info.

1 Like
132

Two quotes from that second link caught my eye.

NASA has funded research and development of new advanced materials to improve aeroponic reliability and maintenance reduction. It also has determined that high pressure hydro-atomized mist of 5-50 micrometres micro-droplets is necessary for long-term aeroponic growing.

For long-term growing, the mist system must have significant pressure to force the mist into the dense root system(s). Repeatability is the key to aeroponics and includes the hydro-atomized droplet size.

and

Atomization (>65 pounds per square inch (Template:Convert/round kPa)), increases bioavailability of nutrients, consequently, nutrient strength must be significantly reduced or leaf and root burn will develop. Note the large water droplets in the photo to the right. This is caused by the feed cycle being too long or the pause cycle too short; either discourages both lateral root growth and root hair development. Plant growth and fruiting times are significantly shortened when feed cycles are as short as possible. Ideally, roots should never be more than slightly damp nor overly dry. A typical feed/pause cycle is < 2 seconds on, followed by ~1.5-2 minute pause- 24/7, however, when an acumulator system is incorporated, cycle times can be further reduced to < ~1 second on, ~1 minute pause.

The first part about droplets penetrating the root mass seems to contradict Atomizer saying never to spray the roots directly. In fact, it sounds to me like they are deliberately spraying the roots directly. Note there is no mention of mist density or hang times.

Also note that they are talking about droplet sizes starting at 5-50 microns rather than 20-80 microns we usually hear.

I sure wish we could find the original research papers instead of some edited wiki.

1 Like
133

Ok, it looks to me like all the original data, research notes, etc were kept by Stoner and are considered proprietary to his businesses. I cant tell for sure - I gave up reading useless links - but it looks like he is mostly out of business. He still has one web site selling some tonic and maybe still HPA nozzles.

I actually tried some of his nozzles and didnt like them at all. The flow rate was 3 or 4 times the rated number and they had zero hang time.

So - it does look to me like the original experiments were done on the shuttle or on MIR. That means zero gravity, but does that invalidate the “50 micron hang time” theory or not? Do we take that info above and ignore the rule about not spraying the roots directly?

I have no conclusions yet. Still processing all this.

I do know that where my roots get too much direct spray, they stay smooth. Which tends to support the rule to not spray roots directly.

On the other hand, the roots in the center of my root mass also tend to stay smooth. That seems to support the idea that you need to force those small droplets into the root mass = spray them directly with some force.

Maybe the key is nozzles that put out more smaller droplets and far fewer large droplets? Im not so sure about that either.

1 Like
134

This quotes are from the Wikipedia, at least the last one. But there are no any links to the sources which is pretty weird for the Wiki.

1 Like
135

Since you asked and Larry started hitting some of the sources I found led me to go ahead and post what I’ve looked up so far:

I think everyone agrees? This article and a few other variants of the same article is the source for the NASA Aeroponics story: https://www.nasa.gov/vision/earth/technologies/aeroponic_plants.html
That article is really just a “summary” of an article found here:

Useful takeaways from the source article:

  1. AgriHouse, Inc ( Aeroponics International) partnered with NASA and BioServe Space Technologies to design a soil-less plant-growth experiment to gauge the effectiveness of a non-pesticide solution on the immune responses of bean plants.
  2. Richard Stoner II, president and founder of AgriHouse, began using aeroponics in the late 1980s to grow herbs in a greenhouse. Utilizing his own patented aeroponic process….
  3. The goal of the NASA research was to determine whether or not the antifungal response of the plants was maintained during space flight.
  4. The success of this NASA experiment led to others, designed by Stoner and his company under numerous NASA Small Business Innovation Research (SBIR) contracts from Kennedy Space Center.
  5. AgriHouse’s aeroponics and ODC research on Mir and its ensuing first SBIR contract made way for the commercialization of the Genesis Series V aeroponic system. With this rapid-growth system, plants can be started from cuttings from an already-mature plant placed in the openings on top of the growing chamber

Some of the potential leads we got from the article:

  1. AgriHouse / Aeroponics International
  2. Richards Stoner
  3. BioServe
  4. SBIR Loans
  5. Genesis Series V system
  6. 1997 NASA missions to Mir

1) AgriHouse (https://www.agrihouse.com/) parent company of: Aeroponics (https://www.aeroponics.com/)

Has the Genesis Series V system for sale (matches with commercialization)… but unsure if they fill orders the website says “Since 2000” and looks like a website from 2000.

This FLEX Aeroponic System model was developed for commercialization as a result of the NASA SBIR Phase I contract for the research and development of a low-mass, Inflatable Aeroponic System (IAS)

Aeroponics International licensed the patent rights of the technology to its parent company, AgriHouse, Inc.

Prototypes developed during the Phase I contract in 1999

2) Richard Stoner - patented aeroponic system.

a. Nozzle based Aeroponics:

b. Rotational mist aeroponics:

  • US6807770B2 - Low pressure aeroponic growing apparatus - Google Patents
  • Neat design… rotating mesh tube with a drip line in it. Rotating tube should help prevent root blockage IMO since it can rotate 24/7 with minimal effect in the root zone.
  • droplets of about 50 to 100 microns in size. The droplets should be sized so as to permit chemical bonding between oxygen species and liquid nutrient solution.

c. List of all Stoner patents: Richard J. Stoner Inventions, Patents and Patent Applications - Justia Patents Search

3. BioServe
BioServe Space Technologies is a Center within the Ann and HJ Smead Aerospace Engineering Sciences department at the University of Colorado Boulder. (BioServe Space Technologies | University of Colorado Boulder)

  1. Flight history: Flight History | BioServe Space Technologies | University of Colorado Boulder
    • Flight 13, STS-86 to Mir Device/Experiment: PGBA-2
    • PGBA: Plant Growth Bioprocessing Apparatus PGBA | BioServe Space Technologies | University of Colorado Boulder
      • Seems to imply this is what was used for the ODC experiments. Makes me question if Aeroponics was used at all.
      • Has a photo of loading it with seedlings prior to flight. Sure doesn’t look aeroponic.

4. SBIR Loans

5.Genesis Series V

  • (Aeroponic System Genesis Series V)
  • High pressure pump unit w/ high capacity accumulator, digital timer (multi-settings/ programmable), 26 ea. spray jets (.025" orifice), power strip w/ GFP, aeroponic chamber (48 in. Long x 18 in. wide x 16 inches deep) w/ 160 plants support structures, stand, nutrient recycling reservoir (7-gal) w/ auto-refill, 3-stage effluent filtration, stainless steel delivery hoses, pre-filter w/ reverse osmosis pure water supply system, drain connectors, reservoir over-flow protection, auto-refill, oil-filled pressure gauges, by-pass valve, additional chambers expansion ports, 85 page installation manual and growers guide, and cleaning tools.

6.1997 NASA mission to Mir

  1. Antimicrobial Agent Updates Ancient Industry of Prayer Mats | NASA Spinoff

    • In 1997, NASA researchers aboard the Mir Space Station and the Space Shuttle used chitosan to protect adzuki bean plants and found the treated plants yielded more biomass and showed greater resistance to pathogens than the control group.

  2. Spaceflight mission report: STS-86

  3. STS-86 - Wikipedia

  4. More confirmation the mission was about disease control not aeroponics itself: NASA announced that Aeroponics International ODC biocontrol will launch on the space shuttle "

In addition, seeds and seedlings treated with ODC appear to have exhibited more robust growth and disease resistance than those without the ODC treatment.

  1. Interesting article with some good diagrams. Aeroponic growing systems for greenhouses and indoors the natural solution for clean aeroponic food indoors
    Pretty much shows nozzles spraying roots direclty

My takeaways:

  1. The “NASA connection” is really an advertisement/quote from Richard Stoner about the efficiencies of aeroponics and how it might work well in space… but not about any specific NASA experiments IN space.
  2. The guy who has been patenting tech for Aeroponics since 1985 thinks that 50-100 Microns is the ideal size
  3. The same guy at least originally used 12 second mist with 40 second rest cycle.

The next thing I’ve seen mentioned a lot is “avoid spraying the roots” I simply don’t believe this to be true anymore. It seems like aeroponics is an evolution of NFT. (Actual NFT, not flooding pipe NFT). The big weakness of NFT is the huge surface area you need to get a very large root structure that you can still reliable and constantly get in contact with the film. Aeroponics turns the air itself in to the film enabling large vibrant root systems.

As an additional argument for spraying the roots, I’d like to reference how gasses perform in a microgravity environment. They don’t move. (I don’t really like Quora, but this question is answered by an astronaut… so) https://www.quora.com/Do-astronauts-on-the-ISS-need-to-sleep-with-a-fan-on-or-in-some-way-have-moving-air-around-them

In an aeroponic system in space, droplets that are not blown in to the plant will not reach the plant.
So you can add fans to the root chamber… except the drops don’t “swirl” that well… so they’re just going to get blown in to the wall for the most part.
Or… you could spray the roots. This would probably cover them in probably a very thin film of mist that you then let get absorbed/evaporate before spraying again.

You could definitely build a system in gravity where you do not spray the roots directly, and I think ONLY spraying the roots is wrong because you do want diffusion around ALL the roots.

Now digging in to additional research:
Ways to make drops:

  1. Ultrasonic misters
  2. Nozzles with pressures (I’m including AAA for now)
  3. Rotational methods

Physics of drops:
The fall rate, drift rate, nutrient concentrations are heavily researched.

  1. Commercial Farming cares about this greatly. They want to spray as little stuff as possible and have as much as possible get where they want it.

  2. Commercial Exterminators/Pest control care about this greatly. They want to spray as little as possible to have the best effect possible. (This group mostly includes fog based sanitation methods)

    The chart Larry has posted seems that it is pretty accurate based on the agricultural guidance I’ve found on pesticide drift. Extrapolating to a measurement more reasonable for a growth chamber
    To fall 1 foot a drop of X microns:
    5 = ~6.5 minutues
    20 = 25 seconds
    100 = 1 second
    240 = .6 seconds

Commercial farming mostly uses pressurized nozzles for liquid distribution. This is great. LOTS of useful info and measured stuff for farm equipment. I like farmers because they mostly want shit that is maintainable, reliable and affordable. Nozzle replacement for their sprayers are easily bought in singles for <$10 per nozzle for stainless. There are reliable charts for running up to ~100 PSI. There’s also defined standards for nozzles and droplet size and performance.

Agricultural nozzles are interesting because they have targeted spray ranges that are “possible” in a home growth chamber…. 20"-30". They’re also sad because the standard nozzle specification for a <60 micron droplet aren’t made by anyone because their drift is way too high for effective use in agriculture.

Exterminators etc, tend to use hot or cold fog machines. The cold machines use low pressures and rotating disks to create fog from 50 microns or less. (IE Vectorfog C20 ULV Cold Fogger) The Exterminator foggers seem really nice for an aeroponic system…. If you’re growing at an industrial scale because they shoot fog at least 5 feet.

Based on all that, I’m very interested in testing out the TeeJet 11001 nozzle tested in this paper: https://www.researchgate.net/publication/233926538_Measurement_and_classification_methods_using_the_ASAE_S5721_reference_nozzles
At 65 psi, 50% of the drops from it are <115 micrometer. That seems pretty good based on everything else I’m seeing.

I’m now wondering if the lingering fog most aeroponic systems are known for even needs nutrients. Could even fewer nutrients be used if the bulk of the “fog” to keep the roots from drying out is done out of pure water, and nutrients are done with a much shorter burst generally aimed in the direction of the roots. Caveats being you don’t want to hit the roots with high speed water and damage them. And your nozzles are going to have to be the “right” distance from the roots… For farming nozzles probably ~30"?

3 Likes
136

Yeah, it looks to me like a lot of the information on this is in the form of circular references - A references B who references C who references A, etc.

Thats kind of what @TexanMD found too - and it almost all goes back to Stoner.

Nice collection of references!! Its going to take me a while to process all that. I already have a few items I dont quite agree with, but excellent info!!

1 Like
137

I’m definitely interested to hear which. So far I’ve done nothing but “academic” research while you have multiple iterations of actual experiments done. So far I feel like I know nothing. All I think I’ve really learned so far is that the NASA connection to aeroponics is more tenuous than i had previously thought.

2 Likes
138

Honestly I think there were experiments. Haven’t got enough time to review all your links but I believe one of them references to the article Progressive Plant Growing is a Blooming Business. Not sure if there was aeroponics on hydroponics but they’ve used a soil-less method with a special nutrient-rich liquid.

Please let me disagree. LPA aeroponics might look like (and I believe it is) NFT. But Atomizer offers the very good point of view on mist as on a medium. Not as a method to deliver nutrients only but as an environment\medium like soil. Water film incase the roots and block air access. I see aeroponics as totally different thing.

The idea of not spraying roots directly is to protect them from any additional force: they seem to not like it. AFAIK air-pruning is pretty effective way to prevent root mass from overgrow. At the same time spraying via HPA and even more with AAA system effectively creates indirect particles movements which eventually should fill every gap. Direct roots spraying will affect only the first layer(s) of roots, it still can’t reach the roots mass in the middle. When you generate mist if push particles with certain force (as a fan does for astronauts), so they get certain momentum and then floating around a chamber. Of course it also disturbs roots but much less than direct spraying.

An an another bad side of the direct spraying is over-spraying the first layers of roots. They do get the idem water film and effectively become hydroponic-type ones rather than aeroponic-type (with a lot of very thin sprouts).

Why do you think so?
Of course, if roots are too dense you are absolutely correct, but I believe such roots impossible to “crush” even with direct spraying without damaging the first root layers.

Very interesting paper, thanks! The only doubt is that it is hydraulic-only nozzles than returns clogging and fine control absence problems. I believe it’s very hard to have very short mist pulses with hydraulic nozzles.

1 Like
139

I think that it will end up acting similar (but opposite) to how CO2 acts around an astronauts face while they sleep. They have to sleep in a room with good air movement or a fan near them to stir the air to prevent a CO2 “bubble” from forming around their head from exhaling.

Sleep spots need to be carefully chosen - somewhere in line with an ventilator fan is essential. The airflow may make for a draughty night’s sleep but warm air does not rise in space so astronauts in badly-ventilated sections end up surrounded by a bubble of their own exhaled carbon dioxide. The result is oxygen starvation: at best, they will wake up with a splitting headache, gasping for air…
(from ESA - Daily life)

Its probably possible to do, but I think would have an important difference in cycle times because the air will not have a tendency to move as much as it would earthbound.

I think that I probably didn’t express this well. I think NFT and aeroponics have a lot of similarities and at least to me, we’re trying to accomplish the “same” goal in having the roots be covered as much as possible in a nutrient solution that is as simple for the plant to consume nutrients and oxygen from. Aeroponics does this with a “dry” nutrient film (due to the small droplet size). Aeroponics is also not limited to the amount of surface area you can provide the plant to lay roots on. its a far more efficient way to deliver the nutrients.

I agree with you about not spraying the roots to protect them. I don’t think most root chambers are built to a size that enables the right size drops to be created AND blown at the roots without damaging them. in which case its better to not spray the roots even though its less efficient and far less of your nutrient is making it to the plant. AAA or a rotational mist generator are probably the best in this regard. AAA because of the extremely low PSI it is able to operate under and rotational because its not “spraying” anything with force anyway.

3 Likes
140

What if you ran a line from a small aquarium air pump into the root chamber. It would keep the air in the chamber moving around and might add some oxygen also?

This stuff is way too technical for me, but just my two cents there haha. Really interesting thread, and very professional build quality on all your equipment!

2 Likes
141

Sorry guys - Ive had a lot going on plus Im fighting some more kidney stones.

Im going to answer your question first because its easy :slight_smile:

Thats a great idea in theory, but it doesnt work very in practice. The air from the pump will be extremely “dry” relative to the environment in the chamber. All the dry air will mean you need to pump in even more mist to compensate. Plus, with HPA and especially AAA, you have more than enough general air, and droplet movement inside the chamber. Look at some of @heathen’s mist videos above. There is tons of movement of the droplets. Also, any added movement just means the droplets will have more collisions with the floor, walls, ceiling of the chamber - remember droplets dont bounce!!! Once they hit something they stick. If they are small enough, they will stay in the air flow, but that flow still increases the collisions.

The dry air being injected is the main problem though.

An alternative idea was to have a fan inside the chamber to circulate the mist. That avoids introducing dry air but it still didnt work. This has been tried by the fogponics guys with little success. It comes back to droplets dont bounce. The fan body and blades will take a large % of the mist out because every droplet that hits a fan part will stick and no longer be available to the roots.

2 Likes