High Pressure Aeroponics

Hey all! Hydromike here!


I am creating this thread so that it can be used as a good informational demonstartion of high pressure aeroponics (HPA) and also to create a place for me to drop pictures and updates of my system. I have been doing a little research over the past few weeks regarding this method of growing plants, called high pressure aeroponics. While the design itself can be tracked back many years, 1970's perhaps, the aeroponic system was revolutionized by NASA in the 1990's by reporting it as the most efficient way to grow plants in space. Studies have shown many benefits of growing plants with aeroponic techniques on both Earth and in space. To name a few benefits:

- Up to 98% less water usage compared conventional growing methods
- Nearly 1/3 the amount of nutrients used normally in hydroponic/soil applications
- Denser growing areas with closer plant spacing
- Remove the cost of soil
- Tomatoe crops can produce four harvests annually rather than two

Athough there are some great benefits to high pressure aeroponics, there are a few downfalls too:

- More pieces/parts to purchase compared to other growing methods
- Higher pump price
- Frequent maintenance (namely dealing with salt buildup on sprayheads)
- System dependent on electricity

Here's a brief definition of the concept:

Aeroponics is the process of growing plants in an air or mist environment without the use of soil or an aggregate medium (known as geoponics). The word "aeroponic" is derived from the Greek meanings of aero- (air) and ponos (labour). Aeroponic culture differs from both conventional hydroponics and in-vitro (plant tissue culture) growing. Unlike hydroponics, which uses water as a growing medium and essential minerals to sustain plant growth, aeroponics is conducted without a growing medium.[1] Because water is used in aeroponics to transmit nutrients, it is sometimes considered a type of hydroponics.
* Retrieved from Wikipedia.com

For those interested in a simple read-through of high-pressure aeroponics, take a look at this article:


For those interested in the specifics of building this type of system, please continue to read!

There are actually two major types of aeroponics, one is the system type NASA produced, and the other type is more widely used and has been adapted to meet the needs of lower cost and ease of maintenance for the at home gardener. The latter type of system is termed as "low-pressure aeroponics." These types of systems rely on the use of a standard magdrive pump coupled with PVC or tubing, and sprinkler heads. Here is an example of this type of system:


Figure 1: Low-Pressure aeroponic system

You can see that the water sprays from a sprinkler head as large drops that can be easily distinguished by the naked eye. These low-pressure aeroponic systems (LPAs) are generally ran on a 24/7 cycle to continually wet roots. These systems do work very well and are easier/cheaper to build than high pressure units. However, they're not as efficient as the high-pressure aeroponic systems. They differ in the pressure that the water/nutrients are shot through sprayheads, and the diameter of the water droplets. Whereas the LPAs produce easily visible droplets, high-pressure aeroponic systems (HPAs) produce, ideally, a 50 micron droplet size. HPAs also run on a much more precise time cycle; To properly run a HPAs, one must be able to control the timing so that the sprayers run 1-5 second/s, then are off for 3-5 minutes. Controlling the timing cycle and creating the proper size mist requires a specific set of components. We will look at those next.
So to recap:
  • As the name suggests, HPAs require high pressures to operate and thus need special components 
  • HPAs require an optimal 50 micron droplet size from the sprayhead 
  • On-Off times vary, but the sweet spot is about 1-5 second/s on, 3-5 minutes off

Studies have shown that plants are more willing to absorb water in 50 micron droplets more efficiently than any other size. It is for this reason that HPAs are more efficient than the LPAs at growing plants. Again, to produce these optimal conditions, it requires a specific set of tools or components. The main components to understand in HPAs are as follows:
     (1) High-Pressure Pumps,
     (2) Pre-Pressurized Accumulator Tanks,
     (3) Solenoids hooked to a relay timer, and
     (4) Pressure switches

(1) HPAs require a PUMP that can produce enough water pressure to create the ideal droplet size of 50 microns. These are generally diaphragm pumps or reverse osmosis booster pumps. They need to produce about 100 psi. The type of pump I am using in my system is the Aquatec 8800 RO Booster pump. It can produce a maximum of 150 psi, so it gives me some wiggle room. I chose it because of its relatively cheap cost compared to other pumps and its whisper silent operation. The Aquatec 6800 RO Booster pump is also a good option as it can create 100 psi. It just depends on how large a system you want if you want to be able to upgrade the size of the system down the road. Other brands like Shurflo are good choices too. 

(2) ACCUMULATOR TANKS are used in many homes that rely on well water. They help maintain the life of a well pump by working as a pressurized water storage device. They prevent the pump from needing to turn on every single time a faucet, or any other type of demand is placed on the system that requires input pressure. The accumulators have a rubber bladder that can be thought of as splitting the tank in half. One side can be pressurized with air, and the other side pumped full of water. Once the pump fills it with water, the accumulator will be able to let out pre-pressurized water, using the air pressure as a driving force to move the water when a faucet is turned on. I like to use a simple example.... the use of an accumulator is similar to a water gun... you pump up air, only to release the water at a higher "pressure" and supersoak your competition, although for HPAs you wouldn't want to drench your poor roots like that evil kid from up the road. 
So you may be thinking, gee Hydromike, it seems like the pump is already creating pressure for the water... why spend the time/money on an accumulator? Well, let me tell you!

Besides john guest fittings ("quick connectors"), the pump is easily the most expensive part of HPAs so extending the pump life is going to cut down on long term costs. That is the first benefit of the accumulator tank - running the pump less. But even more importantly, the accumulator serves another purpose: creating an instant pressure once the solenoid opens so that the spray heads can operate for short intervals with the exact pressure they need to produce 50 micron droplets. If the pump directly provided the pressure instead of the accumulator, there would be a brief period of time where the pressure would be lower than 100 psi, and this lower pressure would create droplet sizes outside our 50 micron range.

Examples of good accumulator tanks are Well-x-trol tanks. They are specifically designed to do exactly what we want in HPAs. I will be using a 2-Gallon Well-x-trol tank, but you can use different sizes. Smaller to save space, or larger to make sure the pump has less on/off cycles. The only consideration to keep in mind for larger tanks is that the larger the tank, the more "stagnant" the solution may become because the same solution will sit in the tank for long periods of time.

***IMPORTANT: Always install a pressure release valve on accumulator tanks. If the pump or pressure-switch malfunctions and doesn't shut-off properly, the tank could become a bomb. The pressure release valve will prevent increases in pressure beyond a certain point. Very important safety feature!

(3) A SOLENOID is simply the item in HPAs that will close the water flow to the system when the timer turns off. It is an electronically operated shut-off valve. You plug in the solenoid into a relay timer. The timer will control when the solenoid opens and closes, and when the plants receive their nutrients. Timers for running the solenoid are best when accurate down to 1 second "on" times, and "off" times in the minutes range. The timer I use is the ART DNe Recycle Timer, but there are many other brands that can be used. I have even seen links around these forums for DIY relay timers which could help cut down on costs.

(4) The PRESSURE SWITCH. This is a component that is either purchased separately, or is built into the pump. The Aquatec 8800 doesn't have a pressure switch so I purchased it separately. What it does is control at what pressure the pump turns on and when it turns off. Its that simple. If you want your accumulator to be maximally pressured at 100 psi, but to be no lower than say 80 psi, then you set the pressure switch to activate the pump at 80 psi and turn off at 100 psi. Again, pretty simple. The Aquatec company manufactures pressure switches made specifically for its RO pumps, and they can come pre-set to 80 psi cut-off, which is what I will use.

Now, this type of system can seem overwhelming at first. I cannot tell you how many hours it took me to find enough sources to verify the items needed to make a HPAs, but it took a good deal of time over the past few weeks. Keep in mind that once you understand the above components though, the rest is just connecting tubing to the parts.

Here are some pictures of HPAs:


Figure 2: Highly pressurized solution emmitted from spray nozzles


Figure 3: Root system inside HPAs


Figure 4: Demonstration of how closely plants can be placed in HPAs
Another key feature of HPAs is with the root system. You will notice that if the system is working properly and your solenoid timing is good, the roots will look fuzzy like so:


Figure 5: Fuzzy root system with maximized surface-area

Figure 5 shows what you want your aeroponic root system to look like. The root hairs help maximize root surface area. If the roots are looking wet and you cannot see root hairs, the system is probably wetting the roots too often and should be adjusted for shorter on times or the sprayheads should be placed in different locations.

So hopefully now you have a better understanding of the difference between HPAs and LPAs, as well as the components required to make a highly pressurized system. Feel free to post comments and questions.

My Aeroponics Setup


1 = Accumulator
2 = 100 psi Pressure Relief Valve
3 = 12V DC Solenoid
4 = Pressure Gauge
5 = Pressure Switch
6 = Aquatec 8800 RO Booster Pump
7 = 200 Mesh Filter

Looking forward to seeing this. I just finished making a low pressure 6 spot aeroponic system for the first time and waiting for spring before i put some peppers/tomatoes and other vegetables into it. Hopefully your high pressure thread will give me the knowldge to try one of these systems out for myself.

Thanks for documenting this.
I'm really happy to see this thread here. My only problem with aeroponics is that I'm too cheap and lazy to set up a system of my own :P

Glad to help! I'm hoping to condense the information enough, but not include too much. If you see anything that is irrelevant or that I need to expand on please share. Over the next week I will post pictures of my HPAs as it's getting setup.
Thanks for the comments everyone! Will be posting pictures soon

Also, willard, I am not 100% sure, but I am 99% sure that NASA funded research of not just zero gravity, but also HPA on Earth.

This website contains lots of information, albeit a old website.



Hydroponic HPA

Basil Germination at 9 days. Left = hydroponics, right = HPA

The above picture belongs to AgriHouse, Inc.


Hydroponic HPA

Lettuce germination at 9 days. Left hydroponics, right HPA.

Again, the above picture belongs to AgriHouse, Inc.
I have been researching the past few weeks and am in the process of building the system. As you implied, calcium buildup clogging sprayer heads is one of the pitfalls for this type of system. Once my system is in place, I plan on soaking them in distilled water mixed with flora kleen by general hydroponics, then scrubbing with soap and water. I also plant to regularly run the system with flora kleen to help cut down on the salt buildup.

If that doesn't work I may move on to an acidic product to get rid of the salt.

BTW after reviewing the article, I noticed it looked more persuasive than informative. I changed the introduction to include information about the con's of HPAs too.
Water softener?

And probably just general cleaning and maintenance (like an oil change in a car).

hydromike, don't forget to add to the list of cons that there is almost no buffer in aeroponics. If something goes wrong, it will go wrong very fast and have a lot more damage than in hydroponics or soil.

Do you think making an outdoor aeroponic lettuce raft would be profitable? I know that lettuce (and another unnamed plant) are probably the only profitable hydroponic plants to grow, but do you think aeroponics has a large advantage in terms of germination and growing time that it could be more profitable than hydroponics? (once you take out costs for parts and maintenance).

Also, would one be able to use solid nutrients in an aeroponic system? Liquid nutrients are so expensive, so would it be possible to buy undissolved nutrients and mix them in yourself like you can do in hydroponics?

I'm really looking forward to see how you do with HPA, maybe I will experiment with it in the future!
havent read all this yet, but i built a high pressure system in like 2011. i have a thread on here if you are interested. its super promising, but the root space issue is one that needs to be solved first.


Both lettuce and basil are money making crops that you could grow in HPAs. From what I have read, smaller setups are more-or-less for a hobby and will be difficult to actually make profit. However, if you stepped it up and grew a substantial amount of crops then it is apparently very profitable. I myself have never grown anything for profit though, so I am just speaking from what I have read. I imagine that faster harvests would help outweigh some of the costs.

Also, I bet you could use solid nutrients if you are vey careful to fully dissolve the salts and use a 150-200 mesh filter to prevent any particulates that didn't dissolve from getting to the sprayer heads and clogging them. Obviously the safest route would be liquid nutrients though.


Thanks for dropping in. I actually used your thread during my research on HPAs : )

What were your on/off cycle times? From what I have read the ideal split seems to be somewhere in the range of 1-5 seconds on, 3-5 minutes off depending on type of pump, solenoid, spray heads, and root space. There are a lot of variables to consider in HPAs, so I think it may be difficult to accurately state what the on/off times should be and that they will vary widely from person to person, system to system. But it would be nice to get at least a bell curve average range that fits a majority of systems.
i played around for a while and i think i was at like 1 second on.
i dont remember the off times. its all about runoff. i was continuously adjusting to achieve 50% runoff.
Thanks for this. I have always been put off by aero-ponics because of heat and complexity. It looks like heat is a non-issue in this set up. Please keep us updated.
I will post more pictures soon. Right now the name of the game is just getting all the pieces connected and making sure the system works. So far so good.

The container is actually plural, because there are 4. The setup is four, 4''x4'' PVC fencing posts that I had previously been using for an NFT setup. I worry that the 4''x4'' may be too small and that too much condensation from the sprayheads may build up, but I am still going to give it a try. If I run into problems then I will upgrade to either a set of 5''x5'' fence posts or make a giant tray with lid similar to a raft type system.

Here are the gullies and the Badboy HO T5 fixture that I am using :


My reservoir isn't shown but it is a 27 gallon tote from the home depot.
I have been researching the past few weeks and am in the process of building the system. As you implied, calcium buildup clogging sprayer heads is one of the pitfalls for this type of system. Once my system is in place, I plan on soaking them in distilled water mixed with flora kleen by general hydroponics, then scrubbing with soap and water. I also plant to regularly run the system with flora kleen to help cut down on the salt buildup.

If that doesn't work I may move on to an acidic product to get rid of the salt.

BTW after reviewing the article, I noticed it looked more persuasive than informative. I changed the introduction to include information about the con's of HPAs too.

its important to point out, and you may have done this already... but you are not running nutes full blast with this system. i was running my nutrients at like 1 quarter strength or maby even lower i dont remember. this + reverse osmosis water ( 80 bucks) makes it very difficult to precipitate calcium at all. if you are referring to the sink faucet type buildup from evaporating water, this does not occus, the roots will maintain easily 100% humidity at all times, no evaporation will occur on the emitters.

i have never had any issues with clogging, and i never once cleaned the system.

its also worth mentioning that there are other ways to generate this type of mist, namely atomization from compressed air. a good example of this is oil furnaces and airbrushes.

i like that little setup. its begging for a small tent tho lol... to add a bit of unnecessary class to it.

i would highly recommend going in a different direction here. i had roots in a 5 gallon buckets, and the roots destroyed them selves in no time at all.
in my opinion you need to design for a thick column of roots that will extend to the bottom of a container, and then spread around on the bottom.
this was not possible in mine because...
1. the interior root column was to large and it essentially filled the entire container. from this i feel like you should go no larger than a 6" net pot. anything larger will give you a massive root column that will not allow mist to penetrate the center of this mass.
2. when the roots hit the bottom, there is no where to go laterally. and they started to come back up the sides of the container.
from this i feel like you you should be looking for a container atleast 20 gallons and more of a squished cube shape than rectangular. this would allow the center root column ample space, and the roots on the bottom plenty of room to run out laterally.

ive looked at a number of containers. heres where i ended up...
1. build a root "tent"
cheapish...pvc or galvanized steel frame with heat sealed polyethylene film coverings. top to be made form 1/4" ABS sheeting cut on a table saw secured with washer head screws.
if you can build these you can then make any container size or shape with simple materials, problem is sealing the plastic.
expensive... 20 gallon brute from rubbermaid. like 40 bucks a pop tho.

these systems just dont seem to lend themselves easily to long term plants like maters.. peppers etc. lettuce and stuff imo are the best way to go here.
Excellent news about the sprayer head not clogging! My birthday is coming up in Feb. so I might have to ask around the family for RO parts.

I also may have to try out your idea if this one does indeed fail. The system is in my living room right now and I share the apartment with my better half of 3 years. She doesn't mind the aero system as long as it looks decent which is awesome but making the system look good does make things harder. She's probably not going to like me getting rid of the rails and swapping for rubbermaides.

The gullies are pretty long though and have a good 8 inches in between each plant. This should give the plant roots some decent sprawling space, but of course only time will tell. 6'' PVC pipes may provide enough extra space if these square fence posts don't.

The system will be up and runnign either tonight or tomorrow afternoon so I will need to decide on nutrient strength soon. I am gunna keep a detailed excel spreadsheet of EC, pH, on/off times, and notes on the reaction of plants. Right now I have two romas, a tiny tim tomatoe, two jalapenos, a bulgarian carrot, serrano, and another unknown pepper plant. So the fact that there are mutiple types of plants in the system may cause me trouble when choosing nutrient concentration but it will also be great to log information on how the different plants react.

Cannot wait till these plants start putting out!!
So things are starting to come together... Made up a batch of nutrients with ~ 0.6 EC or 400 ppm. My tap water is 0.3 EC or 200 ppm out of the spout so the nutrients are very weak.

The misters have found a way to get clogged with the tiniest pieces of plastic from cutting and putting pieces together. Luckily the misters I chose can twist off and are easily cleaned.

My main issue at this point is the stupid pressure switch. The thing is factory set to cut-off the pump at 40 psi and it must be raised to 80 psi for the setup I have. They make the pressure switch so that you must use a 050 hex wrench to adjust the cut-off. This is pretty freaking small and is an odball size to find. After working with it and turning it clockwise/counterclockwise a few times, the thing was stripped. Yeah, stripped after a couple of turns. So now it is set at 60 psi which barely runs my misters and my accumulator is pumped ful of 60 psi pressure, so everytime the misters are used so is the pump, the accumulator is completely bypassed due to lower pressure.

Now I am going to call the company I purchased the pressure switch from and tell them about the crappy product. Hopefully they send a new one at no cost, otherwise I will have to go spree on a $27 pressure switch from another company. A wise man once told me to always have 2 parts with these systems... I am beginning to see why already!

Stay tuned for pictures and I may make a video and attach a link for those interested in seeing the system running.

So I went ahead and replaced my old pressure switch that was factory set at 40 psi pump cut-off. I borrowed a 050 hex wrench to adjust the pressure switch but literally after only a few turns left, a few right, it stripped. Very poorly made. The new pressure switch is factory set for 80 psi cut-off which is perfect for my application since the optimum range for my sprayheads is 35-80 psi.

Now here are some pictures of the plants at day 1 in the system and then at day 5. There is a clear difference in root health between the pictures.