Aeroponics discussion thread for HPA/AAA and maybe another grow

Im not quite ready to start another grow thread, so I decided to open this up for some general discussion on advanced aero techniques, equipment, design, testing, nozzles, or what ever.

Ive been having some PM discussions with various folks, but I think it would help more people if we have these talks where others can participate and share their ideas, ask questions etc.

So - feel free to jump in with any questions, comments, tips, etc etc.

@heathen @Yawningtears @VandalBee @No_Body I know I am forgetting to tag some others…

I am currently in the process of testing various changes in my AA (Air Atomized) aero setup. So far I have killed off at least 8 babies without making any significant improvements in the system as far as getting fuzzy roots. In fact I am zero for 8 so far!! Im getting nice, white, healthy roots and good looking baby plants, but no fuzzies :frowning:

Oh yeah - I should start by reminding everyone that I am obsessed with growing fuzzy roots. You could even say Im addicted to fuzzy hairs on roots. I am almost to the point of not caring if I even get any good bud or not. Almost :wink:

I had been doing fairly well as far as fuzzies, but there has been plenty of room for improvement.

Here are a few fuzzy root pics from past grows. This is what I am after and would like to improve on.


Aeroponics always makes me smile nice roots :slight_smile: how long have you been growing them?


I have some ideas for you, not sure if any of them would be good or bad, if you have already tried them, or if some are even possible (in no particular order):

  1. Some sort of alternating between either micron sizes and/or flow aka changing how saturated the roots get between close to minimum and less than root rot (over saturated)… might be too stressful, but maybe there is a range and frequency that is actually a healthy amount of stress… maybe it makes more/bigger fuzzies or maybe it generates fuzzies from drought then after developed fuzzies gets to absorb a crap ton more (even more faster growth?)?

  2. Some sort of flush/feeding cycle, aka tee fitting to nozzle fluid side w/solenoid for feed and one for flush… no idea what ratio of cycle like 5:1 feed to flush or vice versa

  3. Chamber pressure positive or negative. Don’t know if this is really possible because you would have to have some sort of pressure relief for the drain and the hardest part would probably be how to essentially seal the trunk/foam collar/net cup… positive pressure might force fluid into roots (helpful maybe for root balls/center buried roots)… vacuum might make roots thicker? Maybe this could be cycled as well?

  4. There was once an experiment of running low voltage through a plant… I’m sure there is a ton that could be experimented with this as well… cycles too :wink:

  5. Maybe a cycle of flood and drain mixed in?

K, that’s what I got for now, that could be a handful :joy:


I started my first HPA grow two years ago, but its been AA ever since. Once I finish experimenting with these changes - and actually start getting fuzzy roots again - the next grow will be number 5 for AA. I have only been running autos the last few grows, so that speeds things up.

Thats a lot of ideas for sure! :slight_smile: Dont take this the wrong way, or as an reason for you NOT to try them if you want. I have been wrong once or twice in my life! Unfortunately, I dont think most of them will work very well at all.

Several things here. First - fuzzy hairs are fragile and very easy to loose. Excess water is one sure way to NOT have fuzzy hairs, so any kind of flow is the wrong direction to go. You could be running micron mist in the upper chamber, and NFT or even F/D in the bottom if you let the water build up, but I dont see any reason for that. AA and HPA work best with drain to waste and when you provide as uniform and constant a mist environment as possible. You DO NOT want a wet/dry cycle. Thats a sure way to get smooth roots.

Also, you cant over water roots in hydro as long as the water is properly aerated. Root spend 100% of their timer under water in DWC and they do fine as long as temps and O2 are kept in range. In any kind of aero, it is 100% impossible to over water. The absolute worst that will happen is smooth roots.

You will only get root rot if 1) Water temps in the rez are too hi - over 70F. And/Or if you are using anything organic in your nutes. Only use pure salts. The other cause of bacterial growth is light leaks. They will cause algae growth.

So to avoid root rot - run a sterile rez, keep rez temps low, and do DTW and keep the light OUT :slight_smile: The amount of mist or watering has nothiing to do with it.

Yes. The whole point of fuzzy hairs is an increase in the efficiency of absorption of nutes and O2. Fuzzy roots can get by with a lot less water and lower concentrations of nutes. They also give larger yields.

BUT - the best way to get fuzzy hairs is micron sized droplets AND as uniform and environment as possible. You do NOT want wet/dry cycles if at all possible.

Sorry no. See above :slight_smile:

I love this one! very much thinking outside the box :slight_smile: But - as you say, I cant think of any way to do that or any reason to do it. I have never heard of anyone trying it - probably because it will be very tricky to keep from blowing the plant out or sucking it into the chamber :slight_smile:

There have been a few studies about this and it turns out there may be some benefit.

IIRC, its only been tested scientifically in soil, but there are some possible applications for AA/HPA as far as having a static charge on the roots that will attract the droplets. That could potentially allow you to run a much lower flow rate with less waste.


It turns out that the current flow range that roots can tolerate is extremely low and extremely narrow. I forget exactly, but they were talking something like a few micro-amps max or the plant suffers. Plus, if the current dropped by even fewer micro amps, there was no benefit at all. IIRC it was something like over 25 micro amps caused harm, but under 10 micro amps did nothing.

I cant imagine how you would measure or control current flow in a wet root chamber at those low levels and with the needed precision.

See above :slight_smile:

You should post some pics of your proposed setup and what nozzles and stuff you are thinking of using.


Well, yes, a lot of out of the box thinking and I do have something not mentioned above I will be trying for nute temps outdoors, but I was trying to throw out some crazy stuff cause it seemed you have done prob most of the experimenting with the standard stuff…

For the pressure idea, maybe this could be attempted with very low amount of negative and/positive pressure… I actually think positive pressure might be interesting because I would think in soil there is some weight on the roots which the positive pressure might mimick so maybe it might produce some positive results :wink:

As far as fuzzies go I have a question for you… once created, when you said something along the lines of they could easily be washed away where the roots just become smooth again… do you think it’s possible that they aren’t actually getting washed away and that the fuzzies are just actually laying down against the root so it looks smooth but they are still there?

If that’s what’s really happening, they still may be absorbing more in that state vs a prior smooth state where they weren’t created yet?


I will eventually get to this…

One more thing, did you ever try some sort of scrog/netting setup inside the chamber?

Anything to keep roots off the floor or do you like them to sit in a lil puddle?

Any sort of filter/screen on your drain?

And finally, any thought on AA effect on if you wanted to try and skip veg?


@Larry3215, @heathen

I’ll share my exp so far. Apologies in advance if post is too long.

The issue with this threads is that they get so long that is hard to summarize the info and make it easily accessible. We should figure out a place to keep all the links and info structured and summarized.

I’m totally into drain to waist AAA system. I run 10x8x7 feet sealed room with 6k btu Mitsubishi mini split ac, dehumidifier, Co2, custom made led lights by QB288 V2 & Slate 2 Single Combo from Horticulture Lighting Group, HLG-600H-54B led driver, 2x AC Infinity CLOUDLINE T8 fans that run for 10 min on mid setting every 3-4 hours to refresh the air inside.

If we consider AAA, imo you go all in or u dont do it at all. By that I mean you do design the right way, use the right parts and setup or you dont do it at all. At least this is my experience so far. Compromising on certain parts like low quality solenoids and other parts only makes things worse in the long run. Ofc its ok to use such for experiments, but when you feel comfortable with the design and parts - get quality ones.

Below are some of the parts and sites I use to get my equipment.
Pushfits for the nutrients line - I use 3/8: I used DMfit in most cases and inline water filters like this one: link
Fresh Water Systems site has great selection of DMfit.
I also use Legris LIQUIfit which I think are better, but a bit hard to source. Better coz they are spring loaded and you dont have to put a secure clip. Mainly from link1, link2

Pushfits for air: Amazon, or any other palace you like - they are quite easy to acquire - not like the water line ones.

HPA: Netafim
Unfortunately in the USA you can get only the gray cap as minimum flow rate. In other markets like EU and India they have a different cap with 2 times lower flow rate.
Also on the site below they only sell the purple pin check valve that opens up at 28psi. I got in contact with them and the sourced for me the orange pin which opens at 58 psi, which is what you want for the HPA system. So if you are interested in the orange one - call them or email and ask.

AFD nozzle: Hypro CS301AFD0.7-80 ADF-Hollow Cone 1/8" MNPT Anti-Drip Nozzle

This one is almost impossible to source anymore as when I contacted the manufacturer it said is discontinued. there is also a push fit version which is better. I got mines from upon contacting them and asking for those model numbers. There were able to find some left overs and I got lucky. That was 2 years go. I’m not sure if they still can source any - call/mail - ask.

AAA Nozzles: I dont have a solution for this yet.
I tried the Monster Gardner one, which is ultrasonic - I chopped off the ultrasonic tip in hope it will increase the droplet size, but the nozzle drips and does not produce the desired result. In addition its not fiber carbon, but pure plastic: link, video
I also got in touch with countless Chinese manufacturers - most of them are direct copycats of ExAir, Spraying Systems, BETE etc. All of them did not wanted to offer free samples. Most of them did not even have droplet charts. So its a huge gamble. In addition they wanted min 5 order of around $100 total for 5. I honesty would avoid them unless they want to provide a free sample. Else its waist of time and money.
At the end of the day I’d pay $200 in a heart beat for a proven nozzle (if only someone can point to one), than wasting time experimenting with countless unknown candidates with questionable quality and performance. Time = money.

Lately I wanted to contact this folks as they have dedicated AAA nozzles for our application. In addition they have a plastic version, which should be way cheaper compared to the SS ones.

Other Equipment:
Compressor: FORTRESS 2 Gallon 135 PSI Ultra Quiet + 10 gallon High Pressure Air Tank
The benefit of this compressor is that it has aluminium air tank. Although its not recommended and the pressure regulator screws are glued, I removed the glue and set mine to cut in pressure at 60 and cut out at 100psi.

Tubing: 3/8 blue

Fans: AC Infinity CLOUDLINE T8

Mitsubishi 6,000 BTU Mini Split MZ-FH06NAH

Led driver: HLG-600H-54B

Led lights: QB288 V2 & Slate 2 Single Combo × 9 - the old version without the R spec.


What someone needs to do is a thread where the original post is always updated and keeps track of everything documented and discovered I would say.


I will throw in a brief history of my growing and some of the recent experiments a little later.

Dont let me stop you from experimenting. If you can come up with a way to do it, then go for it. The trick will be to tell if it is the pressure or some other factor that causes any increase or decrease in yield or quality. our plants have so much built-in variation in how they grow, its hard to judge from one grow to the next what worked better and what didnt.

Maybe they are still there but if so, they are impossible to see with the USB scopes I have used. Here are some pics of fuzzy and smooth roots up close.
WIN_20181028_19_03_57_Pro WIN_20181028_19_04_14_Pro

Even if they are still there laying flat, they wont work as well as they would standing out straight. If they are
laying flat, they will be in the surface layer of water that collects on the root. That layer of water will prevent any direct absorption of O2 from the air. It can still get O2 from the water, but the transfer rate will be much slower. Also, the total effective surface area will be reduced because it is laying flat against another surface.

As far as I know, no one has ever had any type of barrier/baffle/grate/mesh/trellis of any kind work out as far as stopping roots in an aero chamber.

Roots will grow through any fabric/screen/mesh other than closely woven nylon, and even then, they will find the tiniest flaw and grow right through it. Check out my Membrane Meniscus threads on here for more details. I think that was the three types of hydro in one tent thread.

The point is, you will have blocked all mist flow long before you can stop the roots. Once they get through your barrier, they will laugh at you and still go for the nozzles and/or the floor. :slight_smile:

My chamber has no puddles. Its all fabric, so any water that gets to the sides, bottom etc, either evaporates and keeps the chamber cool, or drips down into my collection tray - a water heater safety pan. No water puddles up anywhere. The roots that make it to the bottom get plenty of mist. I usually have some areas with great fuzzies and others that get too wet and stay smooth. A lot depends on how full the chamber gets and how the mist flows or drips off the roots above.

Even if there were puddles, the roots would just grow like it was NFT or DWC depending on the depth.

I would think AA would make no difference one way or the other, but I have never tried that.


Wow!! Outstanding post! I need more time to look at all your links, but I Like what I see so far.

I had no luck with the Hypros I used. I had the grey ones with the ADV’s, but they were the lower pressure ADV’s. On top of that , the release point varied all over the place - from the around 20 PSI to almost 40 IIRC. I was not able to get much if any fuzzies and I was running them at around 80 PSI I think.

That first pic above was using these HPA nozzles with added ADV’s and swivels:

They add up to more cost than the Hypro’s or Netafems, but still less than any AA nozzles. They worked great for me. Well, not perfect actually. The mist was probably just a bit too fine, and/or I ran the flow rate too low. The roots grew to the sides more than down and created a huge umbrella structure which ate all three nozzles (mounted hi shooting sideways and down) and effectively cut the bottom of the chamber off from the top. I was running these at 110-115 PSI.

Were you able to get fuzzy hairs with any of the Hypro or Netafim’s?

So far, the only AA nozzles that have worked for me are the Delavan 30609-8. They run about $25ea on Ebay. A little more on Amazon.

In my small chamber, they work best shooting up from the bottom - or at least they did until recently! Last grow I was using two nozzles, but that left parts of the roots not getting good coverage and caused air trimming in areas close to the chamber sides. This time I have three on the bottom, shooting up. I also made several smal changes that allow me to play with siphon heights and angles and orientation. All that plus playing with various air pressures makes for a lot of iterations to test.

Like you said - time is money!

earlier this summer I got two, used Spraying Systems SU2 nozzle setups. I played with them for almost three months in every combination of position, angle, air pressure, siphon height, etc etc etc, and had zero success as far as getting fuzzy hairs. I think they might work ok in a much larger chamber, but the coherent throw distance is just too much for my chamber dimensions. They did produce some good looking atomization though.

Im using a smaller 0.6 HP 1 gallon California Air Tools compressor and an added 5 gallon tank thats actually my old HPA accumulator . It works fine, but I wouldnt mind a larger one. The compressor cycles a lot at higher flow rates.

What solenoids are you using? Im using cheap ones from Amazon.

I keep two extras on hand, but so far none have failed since I changed to AA. I use them for air, but dont need any for the water side since its siphon feed.

Im also using cheap timers from amazon. They have held up fairly well, but the buttons on one older one are getting iffy, so I keep extras on hand just in case.

I am running a separate timer on each nozzle. I liked the way that keeps the mist level more uniform by firing the nozzles at alternate times - but IM not 100% sure its working as well as I hoped. Need more time.

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I think thats going to be more difficult and time consuming than you think. I dont have the energy to do it myself, but if you want to try it, Im all for it :slight_smile:

The posts above from @VandalBee, and I are just the tip of the iceberg as far as the details you need to know to duplicate our setups. Trying to go from there to some other setup is not easy. Thats why I have three or four LOOOOOONG threads covering my adventures. I dont know how you could condense all that into one post.


I know it’s a lot of work, maybe it will be turned into a guide some day by someone with a solid setup anyone can buy and put together.

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My go to place for all high quality and reliable automation parts is

As for the solenoid - I also tried the once you use, but I find them quite unreliable and sometimes very hard to disconnect the tubing. I have 2 and they are absolute nightmare to remove the tubbing when connected.
If you can afford it these are pretty good: link
They have so many different configs, 3/8, 1/4. 120v, 12,24 ac or dc.

My recommendation would be to use a the high flow rate 3/8 12v dc, as you can connect it to a backup car battery in case of power outage. That way if you have a bigger air tank, and car battery you can safely fall back to it in case of power outage and save the crops until the main power comes back online.

For relays and controls, I use 8 relays connected to a PI, that controls the lights, fans, solenoids - basically everything in the grow room.

Here is a very nice educational video series on the grow room automation topic:

I hope that helps.

The Vandal BumbleBee :smiley:


Hah, I’ve seen that home assistant video with the guy using a magnet spinner to keep his nutes stirred, that’s what I was planning on doing one day…

So do you like the Home Assistant?

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Nice stuff! Ive looked at most of the things you listed, but hadnt seen those particular solenoids. You have to look closely at the specs to be sure the orifice sizes are not too small, but they look very nice - and $$ for me.

I agree about the cheap solenoids being difficult to disconnect the tubing. I use a wrench to hold the release collar in while pulling the tubing out, but it can still be a chore.

Unfortunately, my budget wont allow for those nicer solenoids or much in the way of automation.

Tell us more about your growing room setup. Im particularly interested in your root chamber, how you control chamber temps, number and placement of nozzles, timing settings, flow rates, number of plants, drain to waste or recirculating etc.

Oh - do you grow cannabis or something else?

The fuzzy roots in question when they are exposed to certain pressure from the water, don’t even remember the number, they definitely transform into smooth, your microscope is not lying to you @Larry3215! It takes quite a while of huge humidity and no direct water contact to change back to fuzzy. The fuzzy roots are really strange looking under high resolution optics, they are like randomly little hairs growing in random directions. Welcome back!


ok I made you these photos for your root porn collection larry, I know they get your motor running!

oh yah, also it proves the difference between the humidity root and the water root.

300x magnification darkfield.


I don’t grow pot. I’m all in veggies - mainly cucumbers, red bell peppers and variety of herbs. I used to grow a lot of lettuce at some point, but I stooped as we cant manage to eat it all :smiley:

Root chambers: I used to have 2 cucumber plants per 27 gal container from CostCo.

But its to small for 2 plants as the root mass that the cucumber plant builds up over its life cycle is insane. At some point it fills up the entire container and the plant slows down its growth. 1 plant per container is ok.
I managed to get pretty good results - like over 30 lbs of cucumbers per plant in less than 2 months of grow cycle.
Since I have mini split ac now, I dont think I need to control the temp inside the containers. They are all wrapped in Reflectix insulation. During the day cycle I keep 74 Degrees in the room and 67 during night. If the temps inside the root chamber are an issue, one could slowly pump in filtered cold air from outside the room - I have automation for that.
Inside the grow room I have only the lights, oscillating fan and defumidifier - everything else that generates heat like led light driver, air pump, controllers etc is placed outside.

I used a system like this one. That was all before I got hooked to HPA/AAA.

I’m now switching to 67 gal one: link
For the bell peppers I want to use this setup:
Plants in bot sides of the lid - 3 or 4 on each side.
1 AAA nozzle (if I find such that is working) on one of the sides of the container that sprays along the longs side in the middle.
2 HPA nozzles(netafim or afd) on each side.
I want to live the middle unobstructed as much as possible and have the plants on the side to leave room for the nozzle to spray normally.

HPA Design

AAA Design with syphon fed nozzle:

@Larry3215, thx for sharing the delavan nozzle. Does it have Stainless Steel internal parts and only brass shell? I would avoid using any brass (any material that has copper) as nutrients pushes ions out of the metal that could case poisoning in plants. I’m very careful with the materials I use as I eat what I produce. Containers, fittings, tubing, nozzles I use are from pete plastic or such that cant cause harm.

My Grow Room Setup:


Awesome photos - thanks!!

Where did you get the info on the water pressure causing changes in the hairs? id like to follow up on that as it may have a bearing on my current experiments.

Awesome grow room! I wish I had the space, and the budget to do something like that.
I would love to grow some vegies. That would make my wife a lot happier :slight_smile:

Oh boy - I hope you dont mind getting the third degree. I have a bunch of questions!

Keep in mind Im approaching this from a fuzzy hair point of view.

If you were not getting any root rot, then your water temps must not have been out of line. Do you run sterile rez or beneficial bacteria or anything like that?

Have you grown any plants yet with the HPA nozzles or are you still in the testing stages? One comment on your setup is maybe dont get the plants too close to the sides. In my grows, Ive found that when the roots are too close to the sides of the chamber, the part nearest the sides doesnt get sufficient mist and tends to air prune and/or stray smooth unless you are over misting the rest of the roots.

Im also going to suggest you use at least two nozzles - one on each end firing toward the center - or you may end up with uneven coverage. Keep in mind, I am still thinking more in terms of root development rather than plant yields.

I just went back and looked through my HPA thread. The grey Hypro’s I used had horrible hang times and produced very few fuzzy hairs. When I changed over to the stainless HPA nozzles, I got tons of fuzzies - see the first pic in post 1. The nozzles I was using - link above - worked really well - BUT - I had three of them in the chamber early on. I added at least one more late grow to help even out places where the roots had blocked mist flow.

I really think you are going to need more HPA nozzles if you want fuzzy roots.

Your 67 gallon chamber is not that much larger than mine - 55 gallons. So far, the best flow rate for me getting fuzzy roots has been around 4 liters/day plus or minus maybe 15%. I think the best timing back then with three nozzles was around 0.7 seconds ON time x 60 seconds or so OFF time - depending on pressure settings.

I dont think you will be able to evenly fill a 67 gal chamber with a single nozzle in a way that will give you fuzzy roots - at least not everywhere.

That same over all flow rate - ± 4 LPD - has worked well for the AA setup too. The Delavans nozzles have similar flow rates to those HPA nozzles, so the timings have also worked out in the same ball park, but with somewhat longer OFF times - due to better hang times. Its generally been around that same 0.7 seconds up to 1.4 seconds depending on the number of nozzles, where they were placed, and pressures used. Off times have been from maybe 70 seconds up to 90 seconds.

One of atomizers “rules” is you need good even coverage first, then you look at flow rates and set timings to stay within his ranges. My tests seem to confirm most of his numbers.

The problem for many root chambers is by the time you get enough nozzles to get good even coverage everywhere, your over all flow rate is too hi to get fuzzy hairs because if you try to run at really short ON times, the run-on drips and slop in solenoid function makes for a lot of waste and poor droplet size uniformity - you end up with too many big drops and not enough micro drops. So for most folks, its a matter of balancing coverage vrs flow rates.

For your chamber I suspect you will need at least 4 HPA nozzles - two on each long side. You might get by with 2 Delavans - one on each short end, but Thats going to leave areas with uneven mist coverage, and require longer On times. I think again you will be better off with three or four spread out on the long sides. Your chamber is radically different in shape from mine, so I may be way off. You will have to try different options to see what works best.

Ive found that the math can only get you in the ball park - if you are lucky. It can throw you way off unless you measure actual flow rates AND have reasonable hang times.

In the end, the only way to know what works is to watch the roots closely and adjust timing settings, flow rates, etc until you see fuzzy hairs - or dont as is my current status with my newest changes. :slight_smile:

Sheesh - I got side tracked giving you unasked for advice and forgot to ask more questions…

So what timing setting have you been using and whats worked best with which nozzles?

Interesting idea using your air compressor to drive a pressurized rez rather than one of those aquatec pumps. Have you tried this yet? One problem I ran into was when I had air trapped in my accumulator tank. I was running 100-120 PSI in the tank and that air caused major problems. The main one was that that hi pressure air increased the dissolved C02 in the water. That did two things. It drove the PH down drastically, and it caused fizzing in the water when the pressure dropped again - just like in soda when you pop the top. The PH issue was a real pain. Running at lower pressures, you may not have that issue, but you might want to check the PH as the water leaves the nozzles to see if its still within range.

The AA setup looks good other than what I said above - I think you will need more nozzles - maybe.

These have an SS insert, but the water passage is brass at the inlet. I have not been concerned about that because the water only has a very short time in contact with the brass, and over a small area. Plus, Im running fairly low EC levels, so there will be less leaching. If it was a solenoid where the water sat in a brass fitting 24/7, I would be more worried. I doubt you could measure the copper level in the water as it left the nozzle.

But - if your are concerned, they make an all SS version for about 4 times the cost - $25 vrs $110 or so on Ebay. Look for the 30610-6 version. Unless you want to make your own DIY adapters like I did, you will also want the part number 29713-2 SS adapter. Ive attached the Delavan catalogue.

Delavan-SN.pdf (510.2 KB)

Ok, thats enough of me spouting off - for now :wink:

LOL as you can see I have no problem with looooong posts! :slight_smile:

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