Drain to Waste High Pressure Aeroponics

It seems to me that the people who do have success with high pressure aeroponics are the ones who use larger root chambers which allow the roots to grow into the drain water on the bottom? Except I keep hearing people say that there's a lot of bad 'hormones' etc. in the run off or that the plants down the line could end up with nutrient lockout because they get all the "unwanted" nutrients from the plants uphill on the floor's slope and that it just becomes essentially a nutrient film technique or a kind of deep water culture.

I've looked and not found anyone admitting it but has anyone used chemical root pruning in high pressure aeroponics? Sure, you could buy some expensive paint, or you could make it for yourself for a couple of bucks.

"The last general type of root growth control barrier is an inhibitor. Inhibitor growth barriers use chemical control agents or toxins to constrain root growth. One inhibitor system comes from the nursery production trade. Cupric carbonate (CuCO3) mixed in white acrylic paint at 100g/liter of paint and applied to a solid wall or sheet is effective in controlling roots. Higher rates of 500g/liter were damaging to the whole plant, not just the root tips (2). Other copper based products have been used as contact herbicides and barrier components. The duration of the root controlling effect is variable depending on soil moisture conditions."

http://warnell.forestry.uga.edu/service/library/index.php3?docID=156

The commercial versions of this paint use cupric hydroxide, but cupric carbonate is just a "stabilized" form of cupric hydroxide and the powder is generally sold as a mixture of the two.

I wonder if by using this paint and keeping a root chamber 33% bigger than a pot which would be used for a plant of the same age one intends to finish flower if one would get better results. The third bigger is because supposedly aeroponics grows a third faster and so would need more space.

I like to learn about all of this stuff purely for the intellectual stimulation it provides. You guys all remind me of Thomas Edison trying to invent the light bulb and your inventions may some day be used to grow other food crops more efficiently which would make the world a better place.

Just going through your thread..

I'm wondering if you've read much on photosynthesis and spectrum absorption? White light contains all light and is inefficient because the blue and red range are the easiest which are processed by plants. Green is basically not absorbed at all, which is why plants 'look' green because they bounce it back at us. Some of the other colors are absorbed to a degree, and that's why I thought most LED lights included a few "just in case" to include a little of the less efficient spectrums like orange. Here is a linked picture showing chlorophyll's absorption at different wavelengths I just pulled off a random website, while I try to limit plagarism I have personally conducted these same tests in college which show similar absorption results. Although I will admit your specific plant requires a certain spectrum to "flower" and you should really read Ed Rosenthal's work with using blue light only and supplementing VERY far right red light prior to the dark period/reductions in the 12 hour dark period (He say's he started the 12/12 thing).


The ability of LED's to "pinpoint" the most efficient spectrum is what tends to make them have double the efficiency of a HID according to Ed Rosenthal. I.e. a 500 watt LED is the same as a 1000 watt HID. Albeit LED's will only use two thirds of their claimed wattage at peak efficiency. A 500 watt LED would actually draw something like 333 watts making it even more energy efficient. As for penetration, the inverse square law does not apply to LED's like it does for HID's. They quickly lose lumens. As an example, I've talked to the producer of a 300 watt LED light who says the lumens at 6" are ~80k and ~30k at 12". Since they're usually smaller than HID with such a high and efficient lumen output which is only effective at close distance a light mover is a must for full utilization taking into account lumens/sq. ft of canopy. Look at the beam angle for example 120 degrees on a particular LED would mean that 60 degrees either side of the light the lumen output is half. 60-60-60 is a perfect triangle and if you had a LED light 6" away from the canopy then 6" outside the LED is also 6" away but receives half the lumens. If you have a LED with 10k lumens per sq. ft of canopy and a light mover where the light is brought to within 6" of all plants looking down on the canopy then they are receiving adequate light according to the below recommendation of Ed Rosenthal. This would work really well only on a SOG or SCROG as due to the aforementioned rapid loss of lumens on LED in relation to distance.

As for light needed at different stages according to Jorge Cervantes:
seedlings/clones 375 ft-candles
vegatative 2500 ft-candles
flowering 10,000 ft-candles

Albeit for flowering Ed Rosenthal says:
2000-2500 ft-candles but can use up to 5000 ft-candles at 85 degrees and 1500ppm CO2 with ideal humidity, nutrients, etc.

Neither specifies if those ft-candle recommendations are taking into account the coefficient of utilization, but I assume they are (meaning those are recommendations for lumens per square ft. at the canopy).

I'm curious who actually came up with TAG or HPA. I've heard that people credit Stoner and NASA but his patent in 1985 was for a system that utilized standard household water pressure. This is from the U.S. patent database.

"Because a venturi requires a certain pressure and flow in order to provide the desired suction, and because a mist forming nozzle creates a substantial back pressure, means must be provided for effecting the suction action of the venturi while at the same time providing for a mist spray. Such an aqueous mist spray may be characterized as a hydro-atomized mist. While the formation of a fine mist has conventionally been accomplished with a high pressure pump, it has been discovered that tap water, at standard tap pressure may be utilized by first draining the system between the venturi and mist spray nozzles. The flow of water under tap pressure to refill the system is effective to draw a measured amount of nutrient, hormone or other solution from a source thereof into the water line between the venturi and the mist nozzles. The aqueous plant growth promoting composition, such as a nutrient and hormone containing solution, is then sprayed out of the nozzles in the form of a very fine mist. After a measured or predetermined length of time, the flow of tap water is shut off and the system drained. The cycle is then repeated. In this manner, an intermittent aqueous nutrient spray can be provided to the interior of the chamber in the form of a very fine mist for promoting the propagation of roots on cuttings suspended therein. "

Who also decided such short cycles were beneficiary? Stoner said ~12 seconds.

"In operation, plants are sprayed in a timed mist cycle using a short pulse or interval of water pressure. A time cycle duration holding the main valve open for about 12 seconds allows for a velocity sequence of a venturi suction of nutrient or hormone of about 7 seconds before water pressure builds at the mist jet heads causing a venturi back flow, resulting in an actual misting pressure for a duration of about 5 seconds. At this point, the main valve 51 closes and the purge valve 59 opens for about 40 seconds, sufficient to allow the system an incremental drain period within which line gravity drains the system via appropriate drain conduits. The incremental time duration of the venturi suction determines the quantity of nutrient or hormone delivered to the mist jet heads. This can be easily determined and controlled. The system provides an extremely fine high pressure atomized mist of water and nutrient or hormone solution in a short pulse application. "

More on aeroponics...

How does aeroponics save water?

"The nebulizer created a very fine mist. This was very efficient and reduced water consumption up to 70%.
This effect is accomplished when a drop of water is so fine that an air bubble wraps it, maintaining it at
the same height as the roots, thus avoiding that this drop of water touches the floor and
making the process easier for the roots to absolve this liquid. The water in the pumps have
a nutrient solution prepared according to plant needs." -"Development of an Aeroponic System for Vegetable Production"
J.L. Reyesa, R. Montoya, C. Ledesma and R. Ramírez

A backyard cooling mist system used for evaporative cooling should be efficient enough. Of note in the previous study is that they controlled misting by humidity not by timing, but do not specify the humidity the pumps kicked on at. I also think bacteria would need to be controlled. I don't think H2O2 would be effective as it easily breaks up into H2O and O2. A small amount of chlorine could be added to ensure a sterile environment. Humidity would need to stay high enough to keep the roots alive. The catch 22 is that you want good bacteria because it helps plant absorption, but you don't want bad bacteria or the good bacteria to get out of control.

You also don't want the plant nozzles too far away as seen in this study it can negatively affect plant growth. I imagine they were operating on a timer, but the farther away the spray comes from the less spray that makes it to the plant. This is the reason for my cupric carbonate idea..you keep the roots small and close to the nozzles and you keep them from sitting in any runoff. I just don't know if the amount and frequency of spraying would still be so high that the benefits of using a high pressure low flow nozzles would be negated by using an uneconomic amount of water unless you recycle the water but then you run into the traditional pH and N-P-K ratio issues of other methods of hydroponic grow. You still would see increased growth from the easier utilization of water which I think allows the plant to use more energy on actually growing.

"Lettuce seedlings were grown within frames mounted horizontally above a network of nozzles. Plant nutrition and water requirements were provided by high pressure, low flow nozzles, which produced a fog within a chamber which enclosed the plant root zone. Uniformity of plant growth was measured as fresh weight at harvest. Frequency, duration and position of the nozzles relative to the seedlings proved to be critical system parameters which directly affected plant growth. In particular, the head weight decreased as the distance from plant to nozzle increased."-"Fog for aeroponic plant production."
Giacomelli, G. A. ; Smith, S.

Here is an article with much success in using a dehumidifier type setup to grow plants. This would have to be deep enough that the roots never touched the reservoir and it leads me to believe 100% humidity in the root chamber is ideal.
http://www.plantphysiol.org/content/57/3/344.full.pdf

Of note is that with this 100% humidity 1/8th strength Hoaglands solution was used. Whereas in another study 1/2 strength Hoaglands solution was used with misters running 7 seconds every 10 minutes to raise cucumbers to 32 weeks. "An Intermittent aeroponics system." By: Peterson, L. A ; Krueger, A. R.

Of course they were growing different crops.

"Plants absorb or reflect most wavelengths of light . Far-Red light passes through; therefore there is a higher ratio of Far-Red to Red light in the shade. Plants use the Far-Red ratio to detect being in the shade; they grow longer stems to try to reach the light. Notice the peak of green in the visible spectrum of the canopy light; since green light more than other visible colors is reflected or passes through leaves , plants appear green."
Rosenthal, Ed (2009-07-01). Marijuana Grower's Handbook (Kindle Locations 1698-1701). Quick Trading Company. Kindle Edition.

Which goes along with every science and biology class I've ever had. Plants don't really use green. White light is inefficient, it will work, but you needs twice the watts.

I was just reading something interesting and I thought I would share.

"Besides photosynthesis, carbon dioxide also affects root growth. The effects of
increased CO2 availability on roots have been studied in cultures of beet and safflower
hairy roots grown in an enclosed culture system (DiIorio, et al., 1992), and in whole10
plants (Weathers and Zobel, 1992). In the cultures of beet and safflower hairy roots, it
was found that an increase in dry weight was effected by an increase in CO2 availability
up to 1.3,1.5% CO2, respectively. Past that point (1.6 or 2.0% for beets and safflower,
respectively) the mass increase was significantly less and ultimately negligible (DiIorio,
et al., 1992). This suggests that, for roots, an optimal CO2 concentration exists and, once
levels go beyond that point detrimental effects are seen." -https://www.wpi.edu/Pubs/ETD/Available/etd-0121104-221651/unrestricted/jromagnano.pdf

I can't remember if I mentioned it before, but it was found that O2 levels of 10-20% in the water supplied to plant's roots was very beneficial. 40% was too much, 2% was too little. This is important because atmosphere levels are 20% while the most water can hold is ~2%.

So while I realize that my posts generally are entirely too long and convoluted I would like to state in layman's terms that if someone were to run an aeroponics setup that air exchange would be incredibly beneficial. This would allow both CO2 and O2 to reach the roots. Especially if you were running with enriched CO2 of 1500 ppm(or 1.5%.)

" Due to water’s high surface tension and tendency to stick to itself under microgravity conditions,
conventional hydroponic and aeroponic nutrient delivery systems are not feasible (Levine
et. al, 2001). The successful nutrient delivery system must be able to deliver a reliable
nutrient flow without adding stress to the plants in the system." -same source

Now what is the deal with Stoner and Nasa? Levine's study comes after Stoner's but one has to wonder (since I couldn't google the cited study and don't feel like logging into the databases right now) if NASA has ever heard of a surfacant.

Maybe they have..but I couldn't Ctrl+f it.

In this study in 2003 NASA is using wick systems... They're also using two wicks a system..something I swear Ed Rosenthal mentioned being an important factor (2 wicks a sq. ft.) -http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1000&context=nasatr They also use NFT


However the question becomes..how do you get atmospheric O2 /enriched CO2 levels at the root zone in aeroponics? perhaps running a fan into the root chamber and allowing that air to escape through the drain tube.

I.E. top to bottom

plants
air/light sealed top
misting area
misters
fan
water pool or not..but some way to stop the roots from going into the pump..chemically or not (btw I'm now talking about ~HPA with a higher pressure sprinkler pump but continuous spraying like under LPA)
drain-but drain has a T open to the top to allow any air blown in to escape.


The fan blows the air in, the misters push the air into the root zone, the drain allows the positive pressure to escape. Mister position would need to take into account the fan.

This gets the root zone all the O2 and CO2 it can handle while providing adequate particle size for easy root zone uptake. There are some 1hp sprinkler pumps that could accomplish this.

"Perhaps a more complete conclusion is not just that red and blue promote plant development, but also, that green wavebands work against it.....

Analysis of this literature base unveils a common theme, that green wavebands tend to temper, if not negate, the effects of blue and red wavebands. "

http://jxb.oxfordjournals.org/content/58/12/3099.

You mean that Oxford journal?

I'm not saying there is no function to green light, but that it's one indoor growers don't need. The same can be said for far red light during vegetative stages as it primarily passes through the plants and gives them the signal to increase internodal length.

The only reason growers were using white was because that was the technology available. Sure, you can make a HID blue or red but to do so you're basically painting it and reducing total lumens. By using white light LED's you're not being very 'green'.

if plants absorb green they would be likely to hermie turning on green lights during the dark cycle.

sounds like pet flora is the one that needs to study up on green. he claims plants use green but does not say how or why or provide any evidence.