muleface
Well-Known Member
that is crazy, what is the production output doing aeroponics compared to just putting them in the ground?
High Pressure Aeroponics - Pump Design/mister layout/misters...
It is specialized application. The point is to generate lots of small potatoes for use as seed stock. In that context it is great cause not only do you get monster plants that can put a ton of energy into making potatoes but you can harvest repeatedly unlike on plants in soil.
Here is a write up on the system.
-Eskander
muleface
Well-Known Member
That PDF is great. Its well worth reading. Also, glad you are out there helping the worlds hungry!
also, can you explain what they are saying here.
"Farran and Mingo-Castell (2006) used timers calibrated so that the system can work for 10 seconds every 20 minutes. During cool nights its only necessary to activate the system for 15 minutes every hour. During day we need 15 min. after every 15 min. of inactive period."
So what the cycle they used there? 10 seconds every 20 minutes? or something else?
also, can you explain what they are saying here.
"Farran and Mingo-Castell (2006) used timers calibrated so that the system can work for 10 seconds every 20 minutes. During cool nights its only necessary to activate the system for 15 minutes every hour. During day we need 15 min. after every 15 min. of inactive period."
So what the cycle they used there? 10 seconds every 20 minutes? or something else?
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Nope, when I read that I was like WTF? The lower on time at night makes sense but the "10 seconds every 20 minutes" thing doesn't. I think in the end, you just need to optimize spray duration and off time vs transpiration needs and RH in the root chamber. Keep them moist with as little run off as manageable.
-Eskander
-Eskander
The idea of HP is to provide a mist environment where the roots can feed and breathe at the same time, all the time
Ideally you need to maintain a constant level of mist in the chamber comprised of droplets in the correct range, namely 5-80 microns with the bulk being 30-50 microns. If the roots are coated by a film of water, they may as well be in dwc. Dissolved oxygen plays a minor role in a truely aeroponic environment considering how little water is needed to fill a large root chamber with mist, typically less than 10ml (2tsp) per 1000L (264gal).Root chamber RH% is not very useful for controlling the mist, water vapour is a gas which roots dont use. If you monitor the RH% in the chamber you`ll find it takes a long time to peak after the misting pulse and even longer to fall.If that wasnt bad enough,it never drops back to where it began either
In a nutshell, dont use chamber RH% to govern the mist timing if you wont keep the plants alive
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DO is relative to water temperature. Colder water holds more dissolved gas until just shy of freezing. You are right in that the DO in the water is going to be at the cap with even a small amount of aeration but delivery to the roots isn't as uniform as you'd think. The roots have a few effective microclimates. With pretty much any hydro or aero set up, the roots on the outside are exposed to more DO than the roots near the middle.
As for high uptime on the sprayers, that pretty much eliminates being able to do drain to waste which is one advantage but it also causes problems.
"With a continuous fog, the plants become dependant upon the constant mist and interruption of the fog would soon cause loss of plant life. The continuous mist can also contribute to fungal and bacterial growth in the vicinity of or on the plants." [Coston et al., 1983]
"...interval/duration techniques produce healthier, more natural roots than constant fog or hydroponic techniques . The interval/duration spray method conditions the plants to thrive longer on lower moisture levels and also may reduce pathogen infection. Roots propagated with interval/duration aeroponics are much more resistance to interruption of the misting regimen." [Stoner et al., 1998]
-Eskander
I'm probably thinking about this in too ideal of a situation but It seems that if you can find the on time that holds RH around 99% than you would be maintaining equilibrium with uptake by the roots. That would be optimizing for lowest possible water use rather than idealized growth though...Root chamber RH% is not very useful for controlling the mist, water vapour is a gas which roots dont use. If you monitor the RH% in the chamber you`ll find it takes a long time to peak after the misting pulse and even longer to fall.If that wasnt bad enough,it never drops back to where it began either
-Eskander
RH% is a red herring, if you do a simple test you`ll see why If the chamber is at 70% RH prior to the mist pulse, it`ll take 5 minutes or more to reach a peak RH and another 10 minutes for it to drop back to a stable value which will creep ever higher with every misting pulse.
If you use a 15 minute pause duration based on the chamber RH,it will lead to the rapid demise of your plants. A growroom can be well above 70% RH, if you hang some plants up with bare roots, they`d soon be gonners
Constant mist and continuous mist are different things. If you have enough control over the mist, you can maintain the correct ratio of liquid, coverage and droplet size range relative to the chamber volume. Your references highlight the limitations of hydraulic nozzles in aeroponics, the lack of control (quality, quantity and coverage) results in a less than ideal environment. Using the interval may appear to work better but, in reality, its the only option they have to create an environment thats closer to the ideal, but not ideal because the nozzles they used arent capable of providing it
If they conducted the same tests with AA nozzles, they`d likely come to different conclusions.
If the chamber is at 70% RH prior to the mist pulse, it`ll take 5 minutes or more to reach a peak RH and another 10 minutes for it to drop back to a stable value which will creep ever higher with every misting pulse.If you use a 15 minute pause duration based on the chamber RH,it will lead to the rapid demise of your plants. A growroom can be well above 70% RH, if you hang some plants up with bare roots, they`d soon be gonners
Constant mist and continuous mist are different things. If you have enough control over the mist, you can maintain the correct ratio of liquid, coverage and droplet size range relative to the chamber volume. Your references highlight the limitations of hydraulic nozzles in aeroponics, the lack of control (quality, quantity and coverage) results in a less than ideal environment. Using the interval may appear to work better but, in reality, its the only option they have to create an environment thats closer to the ideal, but not ideal because the nozzles they used arent capable of providing it
If they conducted the same tests with AA nozzles, they`d likely come to different conclusions.
RH is a tool like any other. If you use it right it is useful, if you don't than it is at best merely useless. The root chamber should never get close to a RH of 70. You will start pushing the plant into senescence by letting them get that dry. For any system that is working reasonable well, the RH in the root chamber should stay in the upper 90s. This means that if it drops below that, you need to spray. Is using that as your primary control for spray timing optimal? Probably not in most situations. Is it a useful failsafe? Yes.RH% is a red herring, if you do a simple test you`ll see why
No, they don't say that at all. They highlight the effects of basic physics. If you continuously spray perfect 30 micron droplets all at a constant velocity you still create problems no matter how much you are spraying. Too much and you will form droplets all over the out roots which will shield the inner roots from the mist. Get them wet enough and they will all stick together and make that problem worse. To little and you get very little water to the inside of the root bundle. Since the roots on the outside are finer and have more efficient impingement of the mist, they would grab too much. The core wouldn't desiccate since you'd always be near the dew point, but those roots wouldn't contribute much to water or nutrient uptake either. It actually works to your advantage to have variance in droplet size if your goal is to spray enough to coat all the roots while maintaining an airspace between them.Your references highlight the limitations of hydraulic nozzles in aeroponics, the lack of control (quality, quantity and coverage) results in a less than ideal environment. Using the interval may appear to work better but, in reality, its the only option they have to create an environment thats closer to the ideal, but not ideal because the nozzles they used arent capable of providing it
Most of the mist size and velocity studies seem to have been done with compressed air driven venturi sprayers as it was the only way they could tune both the average droplet size and velocity at the same time. The researchers then seemed to move towards simple hydraulically driven sprayers once they had settles on a size and velocity range they felt was optimal.
-Eskander
You dont spray continuously, you maintain a constant level of mist, much like maintaining an ideal air moisture balance in soil Given the right hardware you can add silly small amounts of water to the chamber in the form of mist, literally down to 10th`s of a ml.
You cant replicate the performance parameters of an AA nozzle with hydraulics, its simply not possible. For example, to get the same coverage you`d need to use a lot more hydraulics, which increases flowrate well beyond the AA. You could reduce the pulse duration by the same factor as the number of nozzles. Replicating the output of a one second pulse of an AA using 10 hydraulics of equivalent flowrate, you`d be looking at a 0.1 second misting duration
The 0.1 second pulse wouldn`t generate the same droplet size range even with a accumulator and solenoids on every nozzle.
Believe me, i`ve tested pretty much everything and anything you can imagine and then some.
This single nozzle AA setup delivers full 360 coverage with 5-80 micron mist. Liquid down to 0.1ml per pulse. There`s no way to replicate it with hydraulics but it would be good to see someone try
Given the right hardware you can add silly small amounts of water to the chamber in the form of mist, literally down to 10th`s of a ml.You cant replicate the performance parameters of an AA nozzle with hydraulics, its simply not possible. For example, to get the same coverage you`d need to use a lot more hydraulics, which increases flowrate well beyond the AA. You could reduce the pulse duration by the same factor as the number of nozzles. Replicating the output of a one second pulse of an AA using 10 hydraulics of equivalent flowrate, you`d be looking at a 0.1 second misting duration
The 0.1 second pulse wouldn`t generate the same droplet size range even with a accumulator and solenoids on every nozzle.Believe me, i`ve tested pretty much everything and anything you can imagine and then some.
This single nozzle AA setup delivers full 360 coverage with 5-80 micron mist. Liquid down to 0.1ml per pulse. There`s no way to replicate it with hydraulics but it would be good to see someone try
muleface
Well-Known Member
so it turns out my calculations were a smidgen off. My nozzles are using about 1/4 gallon an hour. Perhaps i have too many misters. I have 12 - .012 misters per 2x4 root chamber, and 4 root chambers. . They are running at about 100 or so psi. For now i have to go back to a closed system.This is an interesting idea. From a nutrient perspective its not really wasteful. I run about 7 seconds every 5 minutes. I have 48 nozzles that run at 1/2 gallon each an hour. So if i was running full time that's 24 gallons a day or 1 gallon an hour. But i'm really only running at 84 seconds of run time an hour, so that's about 34 minutes a day, that would bring my total water usage to 73 oz a day. That's only 4 gallons a week. Hell, I lose that to evaporation anyway. Also, if i need to add more liquid in my reservoir, i can just mix up another gallon at a my normal concentration, because the reservoir should be always at the right concentration. Plus, at the end of the week I throw out my nutrients anyway, i usually make a 5 gallon bucket of it and add water as needed. So really, there is no loss at all. I could toss the large trash can i am using, and use something like a 5 gallon water container with a small opening to avoid evaporation. I don't have to f with PH, The system would be a hell of a lot cleaner, I love it!
This is a great idea...Welcome to RIU.
Just a word of advice, i don't think that guy in the picture likes his picture taken. he looks like he's going to attack!
Please keep the good idea coming!!
MF
The important thing to consider about a film of water is it acts much like a non aerated mini reservoir.The O2 and/or nute content of the film will be depleted long before the water.
Droplets are also self contained reservoirs but with much smaller volume. You could view the mist as billions of individual, bite-sized, floating lunch parcels surrounded by air. A piece of 325 mesh screen is useful for getting an idea of just how small 40-50 micron droplets are..
Droplets are also self contained reservoirs but with much smaller volume. You could view the mist as billions of individual, bite-sized, floating lunch parcels surrounded by air. A piece of 325 mesh screen is useful for getting an idea of just how small 40-50 micron droplets are..
You could shave that a bit by dropping to 80 PSI But that only drops you to 38.5 gallons per week from 42 gallons per week. How big is your reservoir and how often do you end up changing it?
-Eskander
Catch all the liquid from a single nozzle in a poly bag during a single misting pulse and weigh it on a gram scale. Dont forget to weigh the dry bag first so you can subtract it from the final weight. The bag method takes account of mist run on which can equate to more nutes than the actual mist being delivered.
muleface
Well-Known Member
so my plants were not doing great with my on for 5 seconds off for 8 minutes cycle. I changed it to 10 seconds on and 5 minutes off. Things seem to be going much better. I know that isn't how this is suppose to be done. But im too invested now to have dead plants. Any idea as to why things were going poorly?
Any idea as to why things were going poorly?
muleface
Well-Known Member
if anyone is interested, i'm ordering these....
https://naturalfog.en.alibaba.com/product/60469699723-803143403/High_Quality_303_Stainless_Steel_Antidrip_Fog_Nozzle.html?spm=a2700.7803228.1998738836.185.DEKmvS
They won't turn on until they hit around 40psi, so it should keep the droplets more uniform. The sheet says 1000psi, but they make the lower pressure ones too. Anyway, I have to order 100 of them, but if someone else wants some, i can get more on my order. it will save you the hassle of needing to get more then you need.
https://naturalfog.en.alibaba.com/product/60469699723-803143403/High_Quality_303_Stainless_Steel_Antidrip_Fog_Nozzle.html?spm=a2700.7803228.1998738836.185.DEKmvS
They won't turn on until they hit around 40psi, so it should keep the droplets more uniform. The sheet says 1000psi, but they make the lower pressure ones too. Anyway, I have to order 100 of them, but if someone else wants some, i can get more on my order. it will save you the hassle of needing to get more then you need.
There are two versions of those. A low pressure gated at 65psi and a high pressure gated at 350 psi. In theory you can just change the springs out to adjust that but, It would be best to be sure you are ordering the right one. The ones that are linked are high pressure gated.
-Eskander
-Eskander
The brass anti drips are typically 75psi open, 35psi close for the low pressure version and 145psi open, 70psi close for the high pressure version. When the nozzles clog (which they will) they can be recycled into useful brass grub screws using a 10/24 thread tap. The milled edge makes them easy to tighten without tools