# Aeroponic Spray Timing and Ppm Survey



## Redoctober (Mar 20, 2011)

I'm new to aeroponics, but in preparation, I have read many threads on the subject. Everyone seems to have different philosophies on how to time their systems and what ppm they use. So I just thought I'd put this out there for all the aero growers, or those new to aero like myself, to report on their systems so we can compare and find out what works and what doesn't. 

I'll start by saying that I'm doing 1 min on 7 min off with a ppm of around 400 (GH flora series) give or take a few, and a pH of 5.6-5.8. I'm 2 weeks into veg and plants seem to be doing well so I'm not going to mess with anything for the moment. pH does drift up tremendously though, and I have to bring it down several times per day. I've heard, and agree with the idea that you want the roots damp but not soaking. I may even increase the off time from 7 min up to 10 or so.


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## Badbackguy (Mar 21, 2011)

I think as far as the timing goes it would depend on the strength of your spray pump.. To answer your question though, I started out 1 on and 6 off, but then I modified (next time around) to 45 seconds on and 6 off. Reason being, I had a mold problem on one of my golden nuggets. It wasnt huge (only one partially), and that may have been a strain related issue, or not... Since Ive dropped to 45 sec on things in my situation have improved.
I use foxfarm so I sort of rely on their dosage regarding ppm. I just use the ppm meter as a reference when I change the res. I mean, dont get me wrong, for a hungry strain like white wid max, I adjusted my dosage to feed them a bit more, while like a strain like dp-bb, I just went light on the feeding, and I used the ppm to basically monitor and insure things werent going too crazy in the tank. Sorry, but thats really all I got regarding ppm.


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## PetFlora (Mar 21, 2011)

To decide what the best timing is you first have to understand what the _ideal pod environment_ is, and do your best (within budget) to achieve it. Ideally, you want to maintain an environment that is neither too wet nor too dry- 24/7. That can only be accomplished using deep cycle feed/pause times and delivering the nutes under high pressure.. 

Speaking from personal experience, with lots of trial and error (and help), I can tell you even though your plants look good with long feed times, they will never reach their full yield potential using feed times greater than ~ *ONE SECOND*. But that requires a deep cycle timer (I use a Sentinel ~ $120-200), and is of little benefit unless you replace your low pressure pump and low pressure mist heads with high pressure pump and high pressure but low flow mist heads. 

That said, you will get much better results than you are now at least going with timer that has a minimum on setting of 5 seconds ~ $70 at discount hydro stores, your pause cycle would then be around 30 seconds. 

hth


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## joe macclennan (Mar 22, 2011)

i am currently running the nft-1 one on four off. but i have the nrt-1 ordered as i believe in extending dry periods to help promote good root health. i am only running about 950 ppm in veg. and around 1150 two weeks into flowering. they seem to be loving it. ph around 6-6.2 in both and around 5.8-6 in aerocloner.
hope this helps.
joe


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## Redoctober (Mar 23, 2011)

Thanks for the info guys. I have moved to 45 sec on and 9 min off. I'm hoping this gives the roots time to dry off a bit after the spraying and breath some air. My ppm I just up'd to 570 from 470. I'm not going above this though.

PetFlora, I have looked at that Sentinel timer and will get it at some point when I can afford it. I'm not sure what qualifies as a high pressure system anymore because everyone seems to have a different definition of high pressure aero. Some maintain that a true HP aero system is one in which the water droplets are atomized, while others say that to qualify for HP you just need a strong pump. My pump is a 2400gph xtreme, so It'd be tough to get a water pump too much stronger than that, though they are out there. I'm not sure if my mist heads are low flow or not? Do you have any links to such mist heads? When I get some bucks, I'm going to be the guinea pig for the aerolife nozzel/compressor system. I'm not going to get their container, just the nozzel and buy my own compressor cause the one in their video is really loud. That system (which I'm sure you've seen...just google aerolife) could be considered "true HP aeroponic" because it just mists the roots. I think that as much as we like to think of our systems as "aeroponic," I believe they are really a hybrid of true aeroponics and hydro or nft. The roots get sprayed heavily to the point of basically being submerged in water for a short time but then are given decent contact time with air as well in between spraying. There is usually a certain degree of standing water in the tubes, so some parts of the roots are always in contact with water. A better system would have the roots dangling in air, never coming into contact with any surface, so that even if they were sprayed heavily with water, they would have much more air circulation than inside a pvc pipe. 

All that being said, I agree with you PetFlora that a very short burst of spray followed by a aeration period is best. Part of me wonders if a 1-5 second spray time followed by 30 seconds off would in some way wear out a pump faster? I actually don't know what the shortest time is that my timer will cycle. It'd have to be 5 seconds because it takes nearly that long for the water to make it from the reservoir up and around to the tubes.


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## chennemann (Mar 23, 2011)

Redoctober - Even though you have a pump that can move 2400 GPH, it is very unlikely it can do 80+ PSI. The pumps that the people are using for medium/high pressure aeroponic usually do not pump a ton of water, but they are able to create higher pressure. One of the popular ones is the Aquatec 8800. Also the nozzles put out a very fine mist~50-80 microns and are usually very low flow <1 GPH.


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## Atomizer (Mar 23, 2011)

Redoctober said:


> Part of me wonders if a 1-5 second spray time followed by 30 seconds off would in some way wear out a pump faster? I actually don't know what the shortest time is that my timer will cycle. It'd have to be 5 seconds because it takes nearly that long for the water to make it from the reservoir up and around to the tubes.


Thats one of the reasons why accumulators and solenoids have been employed with hp aero. The solenoid takes all the abuse with the fringe benefits of instant flow and pressure, very short duration mist pulses (<1second) and if you use a 12v solenoid, some protection against power failure..at least until the accumulator is empty


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## Redoctober (Mar 23, 2011)

chenneman, it's funny you should mention the aquatec 8800; I actually have one but use it as a booster pump in my RO system. I never knew you could use it in aero to feed nozzles. What kind of nozzles would you use in that case, and how many could you feed with a single pump? Is this the type of system you use?

Atomizer (perfect name btw, it's just what I need) I have heard PetFlora discuss such things but have very little knowledge about how solenoids and accumulators work. Do you have any resources you could point me to where I might educate myself? I'm thirsty for knowledge. I've read many many threads about aero, but I've never seen plans for this type of system or anyone who has one in action. The closest I've seen to a prefab system like this is the aerolife one, but I don't know anyone who's actually tried it.

I'm trying to visualize how this type of system goes one bit at a time so please bear with this humble aero noob; is this an accumulator like what you had in mind? http://www.amazon.com/Jabsco-30573-0000-Pressurized-Accumulator-Bladder/dp/B000O8D5XM

P.S. it just occurred to me, would this be similar to the type of system that supermarkets use for misting produce? You know, those mist sprayers that come on every few minutes to keep the veggies fresh? I wonder what they use? Time to hit up Google!


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## tree farmer (Mar 23, 2011)

Redoctober said:


> chenneman, it's funny you should mention the aquatec 8800; I actually have one but use it as a booster pump in my RO system. I never knew you could use it in aero to feed nozzles. What kind of nozzles would you use in that case, and how many could you feed with a single pump? Is this the type of system you use?
> 
> Atomizer (perfect name btw, it's just what I need) I have heard PetFlora discuss such things but have very little knowledge about how solenoids and accumulators work. Do you have any resources you could point me to where I might educate myself? I'm thirsty for knowledge. I've read many many threads about aero, but I've never seen plans for this type of system or anyone who has one in action. The closest I've seen to a prefab system like this is the aerolife one, but I don't know anyone who's actually tried it.
> 
> ...


https://www.rollitup.org/hydroponics-aeroponics/254876-my-true-hp-aero-plug.html


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## PetFlora (Mar 25, 2011)

Atomizer has helped me tremendously to up my game. Time will tell, but what he says makes perfect sense- *you don't want your roots to get too wet, or too dry.* The only way to do that is with very short feed/pause cycles. 

My Aquatec 8800 is now 2 years old, but only very recently have I reduced the feed/pause to 1/20 seconds, but before it was 1-2 seconds, with like 2-3 minute pause. Time will tell whether the ~ 9 times more frequent cycling takes its toll. I do have a backup.

My mist heads from Reptile Basics. What I really like is they swivel which comes in really handy to position for proper coverage

I have also significantly reduced ppms. Late grow-500, mid-late bloom 6-700, late bloom 4-500, last 2 weeks I cut the amount in half each week

hth


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## Atomizer (Mar 26, 2011)

To be clear, advocating very short feed/pause cycles for all cases is misleading. If a single nozzle fills a 150gal chamber in 5 seconds without exceeding the liquid saturation point then 5 seconds misting is fine.
The timing is based on chamber volume, the number of nozzles and their flowrate, the correct mist setting is one that provides full coverage but doesn`t exceed the maximum saturation point which gives you the unwanted wet/dry cycles.


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## haole420 (Mar 27, 2011)

in a 20"x30"x15" chamber, i'm running 10 orbit nozzles at 55-75psi. i spray for 5 seconds every minute during the day and 5 seconds every 2 minutes at night (my timer has a photo sensor). the triple fogger runs for 50 seconds then is off for 100 seconds. the fogger makes a big difference but can't work without the nozzles, as the spray is what stirs the fog to fill the whole chamber. for stealth mode, i turn off the pump/nozzles and have a 12V 4" computer fan hooked up to 2 D-cell batteries (3V) blowing air into one of the 3" holes.


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## Atomizer (Mar 28, 2011)

For that timing cycle, chamber size and nozzle count, you`d need the nozzles to put out no more than 0.06gph (0.22 lph). I guess the orbits may at least 20x that flowrate.


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## haole420 (Mar 29, 2011)

Atomizer said:


> For that timing cycle, chamber size and nozzle count, you`d need the nozzles to put out no more than 0.06gph (0.22 lph). I guess the orbits may at least 20x that flowrate.


my system goes through about 1gal/hr. it holds 3gal when fully pressurized at 75psi and holds about 2gal when down to 55psi (when the pump kicks back on). pump comes on about once an hour. yes, tips of roots do have little water droplets on them. probably too wet by "true HP" standards, but for $300 the system works fine and performs all the duties that i assign it beautifully 

main limitation for most people is going to be cost and local availability of parts. my timer goes down to 5sec. if i could find a timer that did sub-1sec intervals for $100, i'd gladly replace it, but i'm not sure such a thing exists in that price range. increasing the period between mistings to 5min only dried out the roots partially and stunted growth. increasing the period to 15min (to achieve 0.06gph) would probably kill my plants.

when i run my 8X T5 fixture on full blast, i'll keep it at 1sec/1min day and 1sec/2min night, but when i only have half of the bulbs on (for new clones), i can get away with 1sec/2min and 1sec/5min night.

one thing i did notice is that the very center site (out of 17 sites in a 20x30" rectangle) doesn't ever get directly misted by the nozzles because the other sites block it. the roots on that site looked just like the fine, fuzzy, cotton-candy-like roots found in "true HP aero" systems. leads me to believe that the droplet size achieved by my particular combination of triple fogger and 10 nozzles at medium pressure is pretty close to "ideal" so long as the nozzles never spray mist on the roots directly. also leads me to consider building yet another rig for the nozzles that points them straight down or even toward the outer wall so they don't point directly at the plants whatsoever. their purpose would be more or less to just stir the fog with some turbulence. otherwise, the fog would just sit there at the bottom.

so for those of you out there that have timers with a relatively long minimum "on" duration (like 10sec, 5sec, or even 1sec), DO NOT try to achieve some kind of magical/optimal flow rate by increasing "off" time to something ridiculous. it doesn't work that way. call a spade a spade and just accept that you're not going to achieve a "true HP" system without spending some bucks on a new timer (and 150+psi pump, and new fittings, and new nozzles, and on and on). i'm a cheap ass, so i'm not going to spend $300 on a timer that costs as much as my whole system costs. maybe after a few more harvests...

bottom line is that it's not about trying to match someone else's "ideal" misting times but to determine what the ideal misting times are for YOUR system given the capabilities and limitations of your particular system. trial and error. make an adjustment, monitor closely for a few days, and adjust again accordingly.


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## Atomizer (Mar 29, 2011)

$300? ouch, my timers will do 0.1sec (or less) and cost me $5 to make, i refuse to spend hard earned cash on stuff i can make myself


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## Mike Young (Mar 29, 2011)

Atomizer said:


> $300? ouch, my timers will do 0.1sec (or less) and cost me $5 to make, i refuse to spend hard earned cash on stuff i can make myself


Are you aware of any 555 timer instructions for dummies? I've looked into building one, but I can't read electrical diagrams. Even a part list would be helpful.


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## haole420 (Mar 30, 2011)

Atomizer said:


> $300? ouch, my timers will do 0.1sec (or less) and cost me $5 to make, i refuse to spend hard earned cash on stuff i can make myself


unfortunately, i dropped out of physics when we got to circuits  DIY instructions?


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## wonin (Mar 30, 2011)

im new to aeroponics have been doing flood and drain for about 2years and im just about ready to start my aeroponics into flowering, they were cuttings so have been veggin for about 7 weeks now.

I am using the amazon 32 site which is basically 2 of these costing me 300pounds or about $480;
http://cgi.ebay.co.uk/16-Plant-Amazon-Aeroponic-System-/400199749640?pt=UK_HomeGarden_Garden_PlantsSeedsBulbs_JN&hash=item5d2dc39008

My timer/sprayers were just constantly on 24/7 for first 3/4 weeks then they developed what looked like magnesium defficiency so took all the water out and just fed magnesium for 2weeks but turned off sprayers completely while light is off (currently 6 hours out of 24) and they seem to be doing alot better.

Now what i was adviced was to leave sprinklers on constantly while light is on but some of you are talking about plants getting stressed or even dying if they dont get water for 30mins but the problem i have is i live in UK and cant get those 1min timers anywhere, best i can get is 15min timers

................so what i was wondering is what cycle should i have sprinklers on?? I was thinking 15min on and 30min off and completely off while lights are off would this be ok? Flood and drain are fine to get no water while lights are off for 12hours but im worried about so long in aeroponics. Im using a maxijet1000 pump and 360degrees spinning sprinklers.

anyone that can help or give advice would be great cuz im fuckin freakin out incase plants die as the magnesium problem nearly wiped them out completely n took 3 weeks to look healthy again. ill try n get pics 2more


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## Atomizer (Mar 30, 2011)

Hi Wonin
You should be ok with 15on/60 off at night with the green 360degree spinners, they soak everything and the roots stay wet for ages. It`ll literally be hours before you see any sign of wilting.


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## Redoctober (Mar 30, 2011)

I'm learning a lot from reading your thread Atomizer, thanks for putting me on to it 
I guess I wasn't far off base looking into super market misting systems. 
Seems like what we're trying to do is a scaled down (or not) and less expensive version of those vegetable misting and humidification systems.


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## Atomizer (Mar 31, 2011)

You can use any method as long as it meets all the necessary criteria, unfortunately, the methods that provide the best fit are also the most expensive.


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## Redoctober (Apr 2, 2011)

Well, since adjusting my spray timing to 45s on 4 min off a few days ago, growth has absolutely exploded 
I'm not going above 380-400ppm because this seems to be the "sweet spot." Plants are drinking a ton also, probable because the humidity is low.
I am vegging for much to long on this one but maybe I'll try to do some LST or SCROG to try to make up for it.
Now if I could only defeat these damn spider mites, everything would be a-ok


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## dr.kfed (Apr 3, 2011)

Here's a study done in roses. They found that spray intervals of 3min on every 15min resulted in roses with improved growth: length and
thickness of flowering stems, length and thickness of flower buds and total leaf
number were enhanced. This was compared to intervals of 3min on every 30min. So in this case more frequent sprayings were better.

EFFECTS OF AMMONIUM RATIO AND
NUTRIENT DELIVERY INTERVAL ON ROSES
GROWING IN AEROPONICS
Authors: A. Jowkar, M. Kafi, M. Babalar, R. Naderi
Keywords:
Rosa L., soilless culture, mist chamber, pressurized air
Abstract:
Roses have been grown for centuries because of their aesthetic value in
landscapes, pots or vases as well as their nutritional and therapeutic
significance. This has led growers to search for means of improving its
production by changing the mode of cultivation and the fertilization regime. The
development of a new aeroponic system is reported here. Stentings of Rosa ×
hybrida Prestige were placed on top of separate mist chambers and nutrient
solutions were sprayed on their bare roots by means of pressurized air.
Aeroponically-grown roses were treated with four NH4
+/total N ratios (0.14,
0.03, 0.02 and 0.00 of a complete nutrient solution and two spray intervals
(3/15 min and 3/30 min on/off). Subsequent growth of plants was measured by
number of flowers, length and thickness of flowering stems, length and
thickness of flower buds, leaf and total dry weight and total leaf number. The
middle range proportions of ammonium-N in the nutrient solutions (0.03 and
0.02) improved the growth characteristics of plants including number of flowers,
leaf and total dry weight, and length and thickness of flower buds. The shorter
spray interval (3/15 min) resulted in roses with improved growth: length and
thickness of flowering stems, length and thickness of flower buds and total leaf
number were enhanced.


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## Redoctober (Apr 5, 2011)

Interesting find dr.kfed. I wonder if the rose schedule would translate to other plants? I'm not running a HPA system like they were in the study but maybe I'll try a few days of 3 min on 15 off. It's an interesting experiment to try.


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## Atomizer (Apr 5, 2011)

you should be using seconds (or fractions of seconds) for misting.. not minutes


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## ChronicClouds (May 26, 2011)

I've got my aero unit inspired by high times. I'm running 400gph pump per pipe. each pipe is 5' long and 6" wide (inside). I have 5 sites per pipe with 1 sprayer per site and 1 extra emergency sprayer in the very back The sprayers I'm using are the same red sprayers used for the ez cloner. The timer is set for about 60 seconds on and 5 min off. I have 3 pipes per res. Each res holds 40 gal. I'm running botanicare products with bud candy (so no sweet) and I used to run +1000ppm. Thats way too high!! (at least for me). Now I usually run 400-600ppm and even begin the flowering at a 200-300ppm. During the peak of flowering week 5 and/or six (depending on strain) I may run as high as 600-750ppm but never higher than 800ppm. I cut out everything except for a flushing solution and run for a day. Then I fill with fresh ph'd h2o, let it run for 1-3days and then flush with only ph'd h20 for the remainder of the flush. (Sometimes 3 Weeks) 

I will say I have never seen such growth or Yields!!!


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## hephasteus (May 15, 2012)

wonin said:


> im new to aeroponics have been doing flood and drain for about 2years and im just about ready to start my aeroponics into flowering, they were cuttings so have been veggin for about 7 weeks now.
> 
> I am using the amazon 32 site which is basically 2 of these costing me 300pounds or about $480;
> http://cgi.ebay.co.uk/16-Plant-Amazon-Aeroponic-System-/400199749640?pt=UK_HomeGarden_Garden_PlantsSeedsBulbs_JN&hash=item5d2dc39008
> ...


You can modify 15 min. segment timers to me 50 seconds per segment; This video on utube shows you how http://www.youtube.com/watch?v=xGfV9IUcFxE


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## AeroPonicsWizaRd (Jan 8, 2016)

google " inkbird twin timer " 25 dollars on amazon and flea bay poor instructions but super easy to figure out and has hundredths of a second timing capable through 99 hours work great if you cant program micro controllers and embedded systems , i just started developing a new aeroponics timer with the new atmel chip with multitasking its going to control the whole garden and i got it setup with a twin lcd display 4 channels i program it with a Chinese ir car audio remote and led ir remote sensor to control on and off times on the independent channels for each solenoid works great it graduates the cycle time 100 miliseconds with each up or down button push its really lazy and awesome i can turn on each sprayer with the remote momentarily with the number pad got to finish the lcd display code and ethernet module hookup so i can control it with my phone it has a dht22 humidity and temp sensor as well i'll have to show some pics when i get it in the electronics waterproof enclosure right now its very prototype looking i am using dc solid state relays to control the solenoids and a 10 amp 12vdc regulated power supply the solid state relays are in place till i finish the 4 channel ir44 mosfet control board with leds got to solder the components and i been very busy should have a chance to finish it soon if anyone is interested i am in the market to make and sell these controllers down the road for a lot less then 300 if you add a milwuakee instruments ph controller mc122 with a dosing pump it controls your ph for 24 hour a day 7 day a week optimum feeding with an alarm when it runs out of ph solution slap a gallon jug of ph down on it and adjust to your preference i'm getting one as soon as i can best 180 dollars spent perfect feeding no nute lockout = efficiency!


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## SteelyX (Aug 31, 2016)

Atomizer said:


> $300? ouch, my timers will do 0.1sec (or less) and cost me $5 to make, i refuse to spend hard earned cash on stuff i can make myself


This method?
http://forum.allaboutcircuits.com/threads/need-a-circuit-to-pulse-a-relay-on-and-off.11112/


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## Budley Doright (Sep 2, 2016)

Pretty sure you can pick up solid state cycle timers off eBay for $10-15 and just need power supply and relays, both cheap as chips. As for timings I honestly think that HPA and LPA are two seperate beasts when timing is involved but really only dabbled in LPA and have not installed my booster pump and bladder tank, doubt I will after returning to flood and drain. I had huge issues with root health until I chilled the water and my root chamber was getting way to hot. When I start seedlings in the trays I would only spray every 3 hours or more depending on RW saturation. After roots were established I would shorten that to 1 hour then slowly reduce to 15 on 15 off. Honestly I never notice much of a difference with timing and even a continuos on cycle didn't change plant growth for my setup. I believe that when using HPA spray times become more critical but this is only from lots of reading and no hands on.


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## Marny (Jun 2, 2021)

Hi Atomizer,

It looks like you have a lot of experience with HPA. Is there any way I could contact you and ask for some information? I have a finished system that should be able to run HPA without any problems, but I have a few uncertainties.


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