Thanks for the heads up regarding the unreachable photos. I edited my previous post and now they are showing.
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I know when making fermented plant juices, etc we shoot for a pH lower than 4.0 to stabilize it.
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Same with canning fruits vegetables and whatnot. 
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Sorry folks - I owe several replies but Im feeling a bit under the weather, so more later.
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Hope you feel better soon. Best wishes!
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What jacks nutes should I use for dwc? Looking for something easier than the gh flora series
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As far as I know, the Jacks Hydro kit I linked to above is the go to for any type of hydro.
Now, Jacks isnt quite as easy as the GH flora. GH is already mixed and ready to go. You will need to weigh out the three parts of the Jacks kit and mix up you batches of concentrates or add the powder to your rez (in the correct order) and mix that way.
Its not that big a deal to mix up enough concentrates to make many gallons of nutes, but you do need a decent scale that can measure smaller quantities accurately. Any small kitchen scale or postal scale should work ok.
P.S. Dont mix it up as concentrated as I did. Some of the part A still wont dissolve. I made it strong enough for 1 quart of concentrate to make about 96 gallons of nutes. Next time Im only going for 1/2 or less of that strength.
Well Iām trying to use Aeroponics for something other than a single reservoir, Iām aiming for a growing bed 45 meters long (about 150 feet). I know it sounds kind of crazy and it should cost a lot of money but I think I have a way around that. This grow bed as I said earlier is not for growing pot though but itās useful information anyway. Donāt get me wrong, I wish I could grow pot in there 
.
Now regarding Aeroponics, I did some extensive (and intensive) reading. I know Iām still missing the practical side of it and Iām sure I will continue to learn and I might be wrong about some stuff but I will share what Iāve learned so far about High Pressure Aeroponics either the Hydraulic Nozzle type or the Air Atomization type as you called AAA.
Iām somewhat partial to AAA for nothing more than itās a large scale Aeroponics project that I intend to do (and I might be totally wrong here) but I will explain why throughout this post.
So what is the gist of High Pressure Aeroponics (Hydraulic Nozzle type) as I see it? A minimum 1000 PSI pump and a 0.2mm (0.008 inch) to 0.5mm (0.02 inch) water misting nozzles. You were right when you said that some Aeroponics growers on the internet keep their methods as a guarded secret because I honestly didnāt find much technically useful information from them.
Okay, letās start with a company that makes large scale Aeroponics systems for controlled environment greenhouses and see what they actually use in their system. One company is NorStar https://www.norstarcorporation.com
These guys now actually refer to our usual High Pressure Aeroponics (that runs at 100 PSI or so), they refer to it as Standard Pressure Aeroponics! https://www.norstarcorporation.com/standard-pressure-aeroponics
Then they have what they call High Pressure Aeroponics that actually runs at 70 Bar (1000 PSI), Check their webpage https://www.norstarcorporation.com/high-pressure-nozzles
These guys claim in their informative High Pressure Nozzles webpage https://www.norstarcorporation.com/higher-pressure-fittings-and-nozzles, that a nozzle pressure orifice between 0.15mm and 0.3mm (and even bigger) operated at 70 Bar (1000 PSI) should produce an AVERAGE droplet diameter of about 33 microns. Here is the neat table they have in their webpage:
To achieve a pressure of 1000 PSI and also be able to tolerate what might be a mildly corrosive nutrient water (Because its PH falls under 7.0), NorStar uses a high end (really expensive!) stainless steel continuous-duty Danfoss (thatās a pump manufacturer) Axial Piston Pump (which is one type of pump that falls under the bigger category of Positive Displacement Pumps).
You can read the announcement here: https://www.danfoss.com/en-us/service-and-support/case-studies/dcs/norstar-specifies-reliable-danfoss-pumps-to-power-innovative-aeroponic-irrigation-system/
They specifically used a Danfoss PAH pump (PAH 6.3). This pump is able to achieve a max outlet pressure of 140 Bar (2030 PSI). That safety margin was to compensate for any expected and unexpected pressure drops along the Aeroponics hydraulic circuit and be able to provide 1000 PSI or more throughout the whole system. Coincidentally, the minimum operating pressure of this pump which is 435 PSI is the same figure NorStar quoted as the minimum operating nozzle pressure in the table above. Here is the pump specs:
Just for the uninitiated here, they didnāt just use one pump obviously! They use several PAH 6.3 pumps according to greenhouse size as seen here:
Okay, this 1000 PSI Aeroponics is only NorStarās claim so far but letās challenge that and see whether itās actually true. One secret lies in the word āAverageā droplet diameter as shown in their orifice size table above. I know you might know this information already but Iām writing this for the general public and anyone who might read this.
Most High Pressure Aeroponic text on the internet state that a system working at about 100 PSI and an orifice size of about 0.6mm (0.025 inch) would produce droplet diameter of 50 microns which is actually kind of true! But if we want to optimize and know more specifics then our first question would be: this surely canāt ONLY produce 50 microns droplets! What is the actual distribution of the droplets diameters? Meaning; what percentage of the produced droplets is actually 50 microns and what percentage of the droplets is bigger or smaller than 50 microns, this is crucial if we want to achieve the NASA tested true Aeroponics effect.
So first, letās investigate this mystical relation between pressure, orifice size and droplet size. Now this is an awesome paper from a nice Swedish guy, this paper has no relation to Aeroponics at all, it describes the usage of water atomization for fire suppression: https://www.researchgate.net/profile/Bjarne_Husted/publication/237389286_The_physics_behind_water_mist_systems/links/568e16d708aead3f42edd066/The-physics-behind-water-mist-systems.pdf?origin=publication_detail
So what does this paper say in short? This excerpt is truly useful then:
Notice the part where he says āThe droplet size is reduced considerately up to a pressure of 7 Bar (100 PSI)ā, He is talking here about an 0.8mm nozzle (roughly 0.03 inch). He continues to say that at higher pressures than 7 Bar (100 PSI) the droplet size is reduced at a much slower rate. At first this might give some credibility to the 100 PSI High Pressure Aeroponics system which actually does produce 50 microns droplets. But he then continues to give this figure:
The situation becomes much more clearer now. This figure is for an 0.8mm nozzle (roughly 0.03 inch). A great deal of information can deduced from this figure. First notice the blue curve which is for 15 Bar (220 PSI) which is nearly double our standard 7 Bar (100 PSI) High Pressure Aeroponics system (albeit with a 0.8mm nozzle rather than the 0.6mm recommended nozzle). I donāt think the situation would be much different for the 0.6mm (0.025 inch) nozzle because itās being operated at roughly half the pressure (i.e. 100 PSI vs the figureās 220 PSI).
At first glance this might seem okay, looking at the blue curve 15 Bar (220 PSI), the majority of droplets actually lie roughly between 20 to 100 microns which should be fine. Well not until one tries to re-evaluate this same curve but as a Volume Distribution instead of a Number of Droplets. As you have mentioned earlier in this thred, a doubling of droplet diameter constitutes roughly an eight fold increase in volume. I have recreated the blue curve in Excel (same as the blue curve above) and I calculated from it a Droplet Volume Distribution curve as seen here:
Now the Droplet Volume Distribution paints a totally different picture. A staggering 98.4% of the water volume dispensed on the roots will lie above the 50 microns droplet size and over 83% lie above the 100 microns droplet size. For example, although the first curve indicates that droplets around 50 microns constitute about 13% of the total number of droplets dispensed on the root, the second curve shows that these same 50 microns droplets constitute a mere 1% of the volume of water dispensed on the roots. So it becomes clear that the claim widespread on the internet and quoted in many research papers that a 7 Bar (100 PSI) HPA system using a Hydraulic Nozzle will produce 5-50 micron droplet is unsubstantiated by actual evidence (i.e. measuring the droplet size distribution of such system).
Granted, the subject of drop formation through atomization and drop size apparently is a very very complex one. This webpage https://spray-imaging.com/spray-description.html lists the properties affecting atomization:
It can be seen that if we limit ourselves to water as the injected fluid and stationary air at @25C as the ambient gas then the list above boils down to three variables:
1- Water injection pressure
2- Water velocity (in simplified cases, this can be determined though pressure and nozzle size)
3- Nozzle orifice diameter
4- Internal structure and geometry of the nozzle
Now the internal structure of the nozzle plays a role in droplet formation, size of droplets and distribution of droplet size but I think from the information above and from the nozzle specs I have seen from serious spray manufacturers with actual data (not those manufacturers who used to do drip irrigation systems and are now venturing into making plastic Aeroponics nozzles), I can say that most claims of a Hydraulic Nozzle type High Pressure Aeroponics running at 100 PSI, whatever the nozzle size is, will not in practice produce 5-50 micron droplets and the big majority of the nutrient water volume will be above 50 micron and even 100 microns.
One problem with the Aeroponics setup with 70 Bar (1000 PSI) as described above is that the water volume dispensed per second from the nozzle (Litre or Gallon per minute) will be more than the popular 100 PSI HPA system. Fortunately the relation between water flow rate and pressure in the nozzle is non linear (there is a governing equation for this) as seen here:
This is a misting nozzle from BETE, they claim that most droplets produced are under 60 microns in size (I would add that this is only true if operated at 70 Bar (1000 PSI) and above. As seen, the flow rate at 70 Bar is roughly 2.5 times the flow rate at 10 Bar (145 PSI), so itās not 7 fold as one would initially expect.
I might talk later about an issue I read from research papers, apparently some researchers concluded that shoot growth for Aeroponics is less than that of Hydroponics, but Aeroponics just makes bigger roots. It seems that those researchers came to this wrongful conclusion because they misplaced the Aeroponics nozzle, either they provided too few nozzles to appropriately cover the roots area or (and this is more important) they place the nozzle at a large distance from the roots so the tiny droplets couldnāt impinge and so the root became bigger looking for more nutrient water. I believe that a staple in Aero and Hydroponics growing is smaller roots compared to soil growing (for the same shoot size) and this is logical, if the plant doesnāt have to do much to get the nutes then it shouldnāt need bigger roots to begin with, well unless it is in the process of preparing for a monstrous shoot! This is a good subject to investigate.
Although HPA at 70 Bar (1000 PSI) would be very good for growing, it has some problems:
- The need a high pressure pump, DOH! It comes at a higher price and a higher wattage.
- Nozzles orifice will deteriorate more quickly. If orifice deterioration is dependent on water flow rate, then it will deteriorate roughly 2.5 times quicker.
- As I can see from literature, spray angle is reduced with higher pressures (not by much though), but might will lead to more nozzles to cover the same area.
- Not much information around for using this system for Aeroponics growing but this might change in a few years.
Merits for the HPA system at 70 Bar (1000 PSI):
- Realizing exactly what an actual Aeroponics system should do based in NASA studies.
- Higher velocity streams will make these tiny droplets impinge on the roots even from greater distances and this might actually lead to fewer nozzles because one could cover a larger area without the tiny droplets losing speed and just hang in the air. A good review on Aeroponics and droplet impingement is found here: https://aeroponicsdiy.com/nasa-review-of-aeroponics/
3- Small scale 70 Bar (1000 PSI) pumps can be found here:
http://www.pumptec.com/media/downloadable/ServiceOIPManual_113C.pdf
and here http://www.speedmax.hk/shop/13-variable-frequency-drive
and here https://www.alibaba.com/product-detail/High-pressure-water-misting-pump-fog_60742760191.html
They are pricier though.
Now regarding Air Atomized Aeroponics, I actually like this system a lot and from what I read everywhere (not on Aeroponic sites but from other applications), I can clearly see it has a number of great benefits, let me try to state the benefits and hopefully I donāt miss something:
- It can produce very good droplet distribution. I donāt have solid evidence for this but it seems if the air pressure and water pressure are dialed correctly then this can be achieved.
- The Air Atomizing nozzle uses less water compared to Hydraulic ones for the same droplet size and distribution.
- Nozzle orifices are bigger and less prone to clogging (A major issue with Aeroponics in general)
Cons Air Atomized Aeroponics?
1- Huge amounts of air is needed and as I said if I want to make a grow bed 45 meters long, I donāt know what kind of monster air compressor I should get.
2- Two running hozes, one for air and another for water to each nozzle.
3- Quality Air Atomizing nozzles are expensive.
I should look more into what total volume of air per minute I need if I want to do AAA.
Thatās enough writing for now because my fingers are starting to hurt.
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Oh my god! That post deserves the post of the year award. I am really sorry I can only like it one time.
You have gone way beyond my research. Its going to take me a bit to process all that information and thats not even following all the links!
Ugg, Wish I didnt still feel like crap. A couple of things jumped out at me, but I need to go back and look at it again. I may have just mis-read something.
Awesome awesome awesome post!!!
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Thank you, Iām just trying to gather and provide some useful information about the damn thing! Because for now Aeroponics seems more like a hidden art than science and proven methods at least on our small scale grow.
I tried to trace the origins for the NASA tested 5-50 micron drop size with no success! Imagine that! I couldnāt find the source for this 5-50 micron claim from NASA itself or from research papers associated with them or from anyone else for that matter to substantiate this figure and this is driving me kinda mad actually because it is being quoted so so SO much and I canāt even find the source, lol.
One thing I wanted to ask you, you said earlier in the thread that you avoid pointing the nozzle directly at the roots. Is the water pressure coming out from the nozzle able to actually cut the roots? Or what was the reason exactly?
Also, other than the beautiful roots that Aeroponics is able to produce; did you observe any difference in the shoot size compared to previous growing methods you used or maybe it reduced growing times somehow? Because I have a feeling that this āmightā all be just a hype somehow! Sure Aeroponics still has an impressive set of benefits even if it results in the same growth rate as standard Hydroponics, like disease is less likely to occur and also less likely to infect other plants, less water consumption and less nutrients than Hydroponics. This is all true, but the claims about more growth rates than Hydroponics, Iām not really sure about that!
I remember you said you had a kidney stone surgery, good for you because a dear friend of mine had kidney stones and he was in so much pain it was painful to just watch. Wish you speedy recovery.
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Thanks for the good wishes! Yeah, stones are a bitch. Ive had them since I was a teen. Always thought I had a bad back, and was shocked to find out the pain was caused by the stones. Turns out I make a LOT of the dam things. The last procedure removed something like 6 or 8 small stones and one jumbo stone from the right kidney. At the same time he found the left ureter blocked by 4 or 5 jumbo stones. He cleared them out, but couldnt get to the other 5 or 6 jumbo stone still up in the left kidney itself. Those are on the schedule for early Dec. In the mean time I have stents in place on both sides - which dont hurt as much as the stones, but still no fun at all.
Ok, enough old man talk about aches and pains and problems. I used to hate that when I was a kid visiting my grand parents, aunts, uncles etc, and now Im doing it!! 
Exactly right. Its like pulling teeth to get info from some of these jerks.
I ran into the same thing. I found refferences to the experiment, but zero details, specs, conclusions, etc. I did find one guy selling nozzles that he claimed were based on the design for NASA.
This is all I was able to find. I wonder if the problem is that the tests were done on MIR, so not a US mission? No clue really.
https://www.nasa.gov/vision/earth/technologies/aeroponic_plants.html
And these are the nozzles.
However, in my tests the flow rate was 4 or 5 times higher than the specs and the droplet sizes were no where near 50micron level. There was basically zero hang time. These were the worst hydrolic nozzles I tried.
No, the spray even with 110 PSI hydrolic nozzles wasnt strong enough to damage the roots directly. Its too spread out.
That bit of aero mystique/myth/wisdom comes from a guy who goes by Atomizer or Atom on various forums. He seems to really know his stuff as far as aero - but - he is a jerk as far as sharing useful info about nozzles. He is fine telling you everything you are doing wrong though and he dishes out little bits of wisdom here and there - especially if you screwed up some how and the info makes you look stupid and him smart.
That particular bit of theory seems to be based on trying to NOT over wet the roots. If you spray directly at or on the roots, they get really wet and then grow smooth hydro roots that tend to go straight to the floor.
If you can keep the āmistā flowing in such a way so there is indirect contact from the droplets just drifting around, that does seem to work better as far as getting fuzzy hairs to grow. The ideal situation is to āfill the root chamberā with droplets in the correct size range, while not spraying directly ON the roots. The goal is to create an environment with a constant density of the correct size droplets that are just wandering round aimlessly, at a uniform density in the chamber. Thats the ideal situation - according to Atomizer.
What you dont want is a dry/wet cycle where the roots get really wet, then you have to let them dry out again.
I have had my doubts about that, but it seems to have at least some truth to it. Roots that stay too wet turn smooth. of course, too dry does the same thing as they air prune.
The trick is how to do that without spraying the roots directly. In a small space, its virtually impossible, and it just gets worse as the root mass grows - which it does like crazy when you have a good environment. By even just a few weeks into all of my aero grows, the root mass has been too big to avoid spraying directly. Plus, the roots ignore gravity and grow UP to the ceiling and sideways towards the nozzles. Eventually, the roots cover the nozzles and then things get dicey.
However, once you have a decent size root mass, that has fuzzy hairs, Its easier to keep them fuzzy, BUT - it turns into a game of timing. Just enough ON time to barely wet ALL of the roots EVERY WHERE in the chamber, followed by just enough OFF time to let them drink the accumulated droplets. Its a fine line I have not completely mastered. I always get nice fuzzies in most places, but there are always at least a few roots that stay too wet and go for the floor as long smooth roots. As the nozzles become blocked, or the roots grow to the point the stop good circulation of the mist, some places in the chamber dry out and you get air pruning and loss of fuzzies.
Its a real trick trying to get the environment uniform from top to bottom in the chamber. The droplets always fall, so the top of the chamber is always ādryerā than the bottom. Ive tried nozzles on the bottom shooting UP and the roots go straight at them fast. I tried mid level and upper level with the same results. I just moved two nozzles to the very top of the chamber shooting down. We will see how that goes.
I think one trick is to have enough nozzles and/or have them far enough from the roots so that the mist barely makes it across, but thats tricky too and requires a larger chamber, which means more nuite use and more nozzles - which is an unending cycle.
My root chamber is around 56 gallons (24" diameter x 29" tall cylinder). Every single grow so far, the roots have gone for the nozzles and expanded to fill the space. Well, thats been true as long as I remember to turn the dam timer back ON!!!
As far as shoot size - do you mean the individual root shoots or the total root mass or? Each time I have had some huge tap roots by the end of the grow mixed in with the majority of roots that Id guess are maybe 1-2mm diameter on average - not counting the fuzzy hairs - but there are also a variety of sizes from that 1mm up to maybe 25mm or more for the big taps. The fuzzy hairs can expand to maybe 5-6mm diameter in places but most of mine tend to be more like 2 to 3mm diameter - like a mini pipe cleaner.
As far as faster grow times - I have not seen that at all. BUT - I have also had major issues with bad rez water, horrible PH control, and of course forgetting to turn the nozzles back ON after some adjustment. I have half killed the roots at least two or three times on every single grow. If I can ever do a clean grow, things might be very different. I have a suspicion that killing most of the roots a few times during each grow might slooooow things down just a bit 
I have seen very good yields though even with all those problems. I have managed a little over 7 gms per day dry yield with HPA where my other hydro was more like 5-6 gms/day and my soils grows were just over 4 gms/day.
Quality wise I have no clue, as I dont smoke - I make capsules/RSO/Green Dragon. It seems plenty potent to me, but I have done no testing.
I need to go to bed, so I will get back to your earlier post tomorrow. LOTS to go over there!!
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Day 69
Quick up-date. It finally got to the point where one of the lower nozzles was completely burried in roots and I could no longer push them aside. I had moved the one I could reach up to near the top of the chamber and that seemed to be working fairly well, so I decided to just go for it and moved both to the very top - up in the plant zone - shooting down into the chamber. After some three stooges moves and a LOT of cussing, I got it working pretty well - I think.
Unfortunately - I was really tired and 1/2 stoned when I finished - and - I FORGOT the Fāing timer again!!! Fortunately, I had really soaked the roots in testing, and I noticed it after ONLY about 3 hours, so not that bad, but it cost me a lot of fuzzies - again!!!
Soā¦ I just ordered a 12 volt buzzer/LED/flasher warning light. Im going to wire it into the second timer and use an SPDT switch so that when I turn OFF the main timer, it starts a second timer. I will set the second timer to start the flashing lights and buzzer after maybe 5 minutes of OFF time. The buzzer is 85db, so that should wake me up even if I fall asleep - which I shouldnt do in only 5 minutes.
In other news - how the heck do you treat a grow where 1/2 of the plant says one thing and the rest looks great?
The left side of the grow is the big girl. She has the most advanced buds, and is largest - but the leaves in the mid level have been turning to crap. BUT half the plant still looks great. The other two look great also with just a hint of the same leaf issues in a very few spots.
This is the left side - all the big girl.
This is the middle - mostly the big girl, plus the runt. The runt looks great over all with just a hint of the leaf issue, but less developed buds.
This is the right side - which has grown to be maybe the biggest plant from being the runt at the beginning. It has almost zero issues and the darkest leaves.
By the way I have lowered the EC TO 1.8. The leaves were starting to look too dark to me.
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I keep forgetting this - the Delavan nozzles Im using now only need 4 to 5 PSI of air to work, so relatively low air consumption - but they dont have a long throw - maybe 36" or so. Flow rates are low too. You should be able to calculate the CFM needed once you have the chamber sizing figured out and how many nozzles it will take to āfillā the chamber.
More later.
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Just got outta jail whats good biys.
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When I harvested my last HPA plants I had one plant that was half purple, half green. I fought that plant all through its growth with differences between each half of the plant ā I never did figure out what the issue was.
I wonder if itās something with half the roots getting soaked and the other half being nearly dry, or something? Maybe not enough nutes to the whole root zone. When I dissected the roots at the end of the grow I had an outer layer that looked healthy but the inner looked like total crap, dying off, brown, and slimy. That was the last straw for HPA with me.
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Oh man, I thought it is a one off! Maybe you have tried some natural remedies that kinda dissolve these stones over time? Well, I guess we have entered the complaining phase, every now and then I catch myself becoming more and more like my parents
Yes exactly, I ran into these webpages too without luck. When I first checked these guys Aeroponic growing systems for greenhouses and indoors the natural solution for clean aeroponic food indoors I thought to myself they are a bunch of hacks! Their plastic nozzles and their pump look like something that was made in a garage rather than a factory. Then, the same as your experience, I saw people talking about these nozzles on other forums and they didnāt like it either. These guys are so lazy they even put the orifice sizes wrong! So much for their āNASAā tested claims:
Oh wow, thatās very interesting information that I wasnāt completely aware of. So what you are saying is that if you had a huge chamber, these problems would have not occurred! Because you would have simply put the nozzles far enough sideways from the roots, the droplets would fill the chamber and you would have avoided these problems! But of course it becomes impractical.
Pot grows (tell me a quick thing, are we allowed to refer to it as āpotā here? Iām not very active on forums nowadays but a few years back; there were some rules to this, Just asking! ) , well it grows huge roots and thatās a problem, other small plants like some leafy greens donāt have these huge roots, so this problem is reduced somehow.
So spraying the roots directly made them wet, yeah thatās logical. I would assume thatās because small droplets accumulate on the roots and bind together forming larger droplets that make the roots wet, which obviously defies the purpose. So I bet youāve tried making the spray ON time very short so that wonāt occur, were you able to make them short enough? I kinda remember you saying 0.5 second, thatās like very short! were you able to do that with your setup or were there other complications?
Roots growing sideways towards the nozzle and ignoring gravity is such a strange phenomenon, you posted some photos where that was the case, these were damn strange!.. After a bit of thinking, maybe itās not that that strange because even in soil grow, roots will go sideways instead of down if they found a source of water on the sides, I just didnāt imagine roots in air would do that as well because thereās nothing to support them unlike soil.
Then roots going to the floor is also strange, it seems as if they are being tricked, thinking the water is straight down as the water droplets accumulate then slide on them and drip to the floor. But I have a question, if droplets are filling the chamber, why do the roots still grow in the direction of the nozzle? Are they looking for more water?
How long do you think the droplets stayed suspended at the top of the chamber, a matter of seconds or minutes?
Sorry, I wasnāt being very clear here, they normally call the part of the plant above ground the āshootā which is opposite to the root. But the fact that you still had good yields despite all these problems is impressive. I didnāt totally get what you mean by grams/day! You do harvest at the end like the rest of us, donāt you? 
Now thatās one strange phenomena, I had these same bad leafs before but in a hydroponic grow, drove me crazy until I increased the EC and it just went away. But again I suppose that this plant is getting the same treatment (root-wise) as the other plants! Very strange.
From my preliminary calculations using a Hydraulic nozzle, I will dispense a maximum of 1 liter per minute when the plants are their biggest size (this figure is without regard to the number of nozzles as it signifies total nozzles flow rate), Iām not sure yet of this figure but itās based on the total water consumption during the life time of each plant multiplied by the number of plants, this will get the average consumption, then I multiply the average by two to get the max consumption, very rough but itās something nevertheless. For now, Iām planning to do drain to waste (Thatās is to save myself the headache of EC and PH fluctuations associated with HPA as I read over the internet).
From Air Nozzles datasheets, they had tables indicating the volume of air related to the volume of water. The lowest I have seen is 400 fold. So 1 liter of water per minute means 400 liters of air per minute. That equates to 14.13 CFM. Thatās kinda big figure because I think CFMs written on commercial air compressors are not actually true.
So this is a tank-less air compressor Amazon.com
It can output 4 CFM at 40 PSI, if it can output 16 CFM at 10 PSI, that would be great. This needs further investigation though.
But (and I might be wrong) the chances for an air compressor are slim because all high pressure misting/fogging systems use water pumps instead of air compressors. I think thatās because it would need more power to generate the volume of air required, much more than an efficient water pump. A water pump running at 1000 PSI at 1 Liter per minute flow rate would optimally be around 1/4 KW or 1/3 HP. Ah, Iām using solar energy, thatās a piece of information I should have mentioned earlier 
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Hi there SuperiorBuds, in your grows with HPA where you faced this phenomenon, where did you place the nozzle? Top, middle or bottom? Facing the roots or away from the roots? And how many nozzles? Big tank or small one? too much questions 
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Thats the only thing I can figure too - but - the other two girls are not showing the signs nearly as bad and they have been through the same crap. In fact, the big girl has always had the largest, best looking roots - and thats where the worst leaves are now.
On the other hand, nothing else makes much sense to me.
Or - is it just an age thing as the plant gets near the end of its days? Ive seen lots of grows where the leaves start turning to crap at the end. But still - why only part of the plant?
I didnt have any slime or smell when I ended up last time. (edit: Looked at my notes and I did have three small spots of root rot) However, there were lots of areas with totally smooth, slightly brownihs roots though - especially in the middle where they were very tightly packed.
I suspect part of your problem was temperature control in the root chambers. IIRC, you had hi temps in the root zone? I have always had to heat my root zone to keep it from being too cold. The fabric pot root chamber cools really well, plus its outside the heated grow space.
Either way, its sure frustrating trying to diagnose issues when you are getting such conflicting messages.
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No worries, Iāll answer everything I can.
I had 4 nozzles per grow bed with 2 solenoids for each āhaloā. Hereās an early shot of the basic layout.
In my configuration I could raise and lower the halo and rotate the nozzles in any direction. By the time I ended I had them nearly to the top, with the nozzles facing towards each other to create a circular motion of mist around the roots.
I was running a 2 gallon accumulator @ ~120psi ā no air assist.
Yeah, I think that was a big part of the problem with the compacted roots too.
Itās like normal solutions donāt apply in HPA, and everything has itās own set of rules. I agree, frustratingā¦
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Pretty much. Bigger chambers are much easier to keep the mist from directly spraying the roots. The downside of course, is it will then take even more spray volume (longer ON time and/or more nozzles) to āfill the chamberā with mist. However, IF your droplet sizing is close to the mark, you should have good hang time of the droplets. That extra hang time means longer OFF times, which lowers your average flow rate. Achieving good droplet size distribution is critical. Im having much better results now that I have switched to AA. It seems to get significantly better atomization than pure hydrolic - at least at the pressures and with the nozzles I was using. Going to 1000 PSI may work better, but those charts you posted earlier didnt look that much better than low pressure hydrolic charts Ive seen as far as the sauder distribution.
Im in a legal state, so I dont care what you call it
As far as root size - thats a very good thing to think about. How big do the roots get with the plants you intend to grow? Also, how long is the grow cycle from the time they will be in the system to harvest? If the plants you intend to grow have smallish roots and/or grow very fast, then you may not have any of the root issues I have had with nozzles being over grown. That could simplify your build a lot. It could also allow you to get by with a smaller root chamber. Smaller should = cheaper. Might also be easier to keep cool. Roots and heat dont mix well at all. Root rot loves warm moist areas. I am of the opinion thats why many folks who do DWC have issues. The roots are sitting in water in containers that are in the heated grow space. That makes it very dificult to keep temps down - requires chillers etc and/or use of chlorine etc to sterilize the water. That in turn keeps fuzzies from growing.
Id recommend you take a close look at the plants you want to grow and see if you can figure out how much space the roots will need. Pot plants grow huge root masses. I know some plants have much smaller roots and/or grow much faster. I think you need to establish that first.
Then you can decide on the size/shape of the root chamber(s) and start calcs on number of nozzles, spray angles that are needed, throw distances, flow rates etc.
Yup, thats it exactly. Small droplets accumulate and then a large droplet ends up sliding down a root and hangs on the very tip. That fools the root into thinking that it has found water (at last!), so it trys to grow down more to get into that new water source. Of course, that just makes it get longer until it reaches the floor of the chamber.
The roots are very very very good at sensing where the water is coming from. When the nozles are on the bottom of the chamber shooting UP, two things happen. The roots can tell where the source of the droplets is and they grow toward the nozzles - every single time. At the same time, the mist is flying up to the top of the chamber, where it gets the ceiling wet. Some of the droplets do bounce, and there are drips, etc from the ceiling, so other roots can sense that and grow UP to the ceiling and then across to the point where the mist stream is hitting. Then they grow like crazy having found a new source of wet.
I think this is all very cool stuff, but it makes it difficult to keep the nozzles clear and keep the chamber open enough so the mist can circulate everywhere. Everyone who does HPA or AA seems to have this issue. From the reading Ive done and the pics others have posted, one key thing is a large enough root chamber. Smaller chambers have more issues sooner with nozzles getting blocked.
Not long - any where from 5-110 seconds depending on which nozzles. The AA Delavan nozzles work far better as far as hang time than I was getting with the hydrolic nozzles. That tells me I have better size distribution with the AA nozzles - or at least more of the smaller droplets than with straight hydrolic.
I posted a video earlier with a cat toy lazer shooting down into the chamber through the hole for the net pot. It was positioned so that when the red lazer line disappeared, that was right at 6" down from the ceiling of the chamber.
With the hydrolic nozzles, the red line was gone in maybe 5 to 10 seconds. With the AA nozzles it took 110 seconds for the mist to drop 6" from the ceiling. There was still good solid mist lower down.
Here is the video. The lazer is sitting at the top of the hole shooting down toward the bottom of the screen. When it gets to the bottom of the hole, you are looking 6" down into the chamber.
I have a chart that tells how long a droplet will āhangā based on its size. I forget now where I found thatā¦ maybe when I was looking into HVLP sprayers.
Anyway, its amazing how long small droplets will hang. Has to do with the surface area/volume/weight ratios.
Looking at that chart, if my droplets fell 6" in roughly 2 minutes, that works out to taking 40 minutes to fall 10 feet. That would imply that those droplets are sub 20 micron on average and probably closer to 10 micron. However, the mist in the lower sections did not last 40 minutes. More like 5 at the max. Other videos I have show that the majority of the droplets are much larger and drop much faster. That spreadsheet you did in your first post is telling about the volume distribution. Most of the nutes drop to the bottom very fast and never touch a root. That tells me there is a lot of room for improvement as far as efficiency in HPA or AA.
crap - gotta run - more later
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