High-pressure (aka "true") aeroponics - nutrient schedule?

He got 1.4 grams per watt on his last run (no journal or public pics, was a single 600W bulb); of course, he's a fricking monster and sets a high bar, but I'm just letting you know.

Unless you're pulling 1.1ish g/w, then he is doing 20% better than you.

His new pods are the craziest looking shit I've personally ever seen (again, no pics, sorry), and I'm gonna do my best to replicate them as best I can when I retire my PVC and build some proper pods for trees.

Bob Smith said:

He got 1.4 grams per watt on his last run (no journal or public pics, was a single 600W bulb); of course, he's a fricking monster and sets a high bar, but I'm just letting you know.

Unless you're pulling 1.1ish g/w, then he is doing 20% better than you.

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Bob Smith said:

His new pods are the craziest looking shit I've personally ever seen (again, no pics, sorry), and I'm gonna do my best to replicate them as best I can when I retire my PVC and build some proper pods for trees.

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response edited and sent privately as it has nothing to do with nutrients...

I'm not sure what direction I'm gonna go with this - still bouncing some ideas off of TF and staring at his newest pod and trying to figure out which features I could/should incorporate, and which I would be overkill for my setup.

For my needs (a 1.5# plant, tops) I think I could get away with 35-40 gallons - he did 1.5#ers in 22 gallon buckets (which he later stated weren't big enough).

Four plants around 1800 watts, I'd expect somewhere in the 1-1.5# range per plant once dialed (if I got four 1.5#ers, I'd be pretty stoked, obviously).

Although his newest pod is really cool-looking, I think for my purposes I could get away with buying some Brute trashcans, although I need to do a cost/benefit and see what the price difference would be - his is for 3-4 pound trees, which I wouldn't come anywhere close to (at the present time).

BTW, got banned from IC for politely telling Rezdog that he was wrong about something, so obviously my journal won't be completed on there (I could sign up with a different name and finish it, but any website that ridiculous is one I won't be visiting again).

Biggest changes for my next setup are going to be:

1) solenoid right before every nozzle
2) possibly some more expensive nozzles (like Bete) that don't crack at less than 80PSI so there won't be any dripping - of course, this would relax change #1 because I wouldn't need a solenoid before every nozzle.
3) Obviously the pods
4) Redesign my plywood box to have two pumps/switches in there (as a backup if the primary goes down)
5) Possibly design some air circulation in the pods, still unsure of that - maybe a cooler/heater system for the roots, but again, wondering if that's necessary - plants and roots actually grow higher at higher rootzone temperatures, assuming proper DO can be supplied.

Another thing I was thinking about was instead of having the solenoids operated by a timer (the timer would still function), I might have a timer for each pod; that timer would then be hooked up to a humidistat (sensor inside the pod), so whenever the RH dropped to a certain %, the humidstat would deliver power to the timer and a quick 1 second pulse would be fired from the solenoids.

Would need some dialing in the figure out the "best" RH% at different growing phases, but (IMO) this would eliminate a lot of the guesswork on timing and whatnot.

Anybody have thoughts on that idea? Has anyone kept track of the RH inside their pods and how it fluctuates, and what RH% is "best"?

A humidistat to control the mist won`t work, the roots will be too dry well before the humidistat senses the drop in RH. With a 40gal chamber at 68F, an increase in RH from 50% to 100% takes 0.04oz of water.

Atomizer said:

A humidistat to control the mist won`t work, the roots will be too dry well before the humidistat senses the drop in RH. With a 40gal chamber at 68F, an increase in RH from 50% to 100% takes 0.04oz of water.

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Why do you say that? Realizing that it takes a small amount of water to raise the humidity, that doesn't mean that the RH will go from 100% to 50% in the blink of an eye, but would be a gradual process from 70% to 69%, etc. - I don't understand your logic in saying it won't work - could you clarify that for me? I must be missing something........

I`ve looked at mist control using RH several times, if you do some research you`ll discover the reasons why its not viable. Here`s a few.
The RH in 40gal chamber with active misting will rise a lot faster than a 10ft room. Once the chamber walls are wet they help to maintain a higher RH reading in the chamber, RH alone won`t supply the roots with water or nutes
RH doesn`t provide any guide to root moisture either, an ultrasonic fogger can raise chamber humidity but it can`t support large roots.
RH measurement relates to liquid in gaseous form, 30-80 micron droplets don`t register as RH until they evaporate, and once they`ve evaporated the roots can`t use them.

Bete`s don`t come with adv`s but they should considering how expensive they are They`re not even available as an optional extra afaik.
Maybe you are thinking of Fogco nozzles, they offer 70psi and 145psi opening but like all adv`s the closing pressure is lower than the opening pressure.

PetFlora said:

BobS, please let me know when you source those high psi mist heads.

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Just go to Bete.com, they've got tons to choose from (but they're pretty expensive) and you need to source them from Bete; I'll let you know what I come up with.

Atomizer, so I'm guessing that you've "looked" at this but never "tried" it, correct?

1) If you're misting the correct amount, the chamber walls shouldn't stay very wet at all, right?
2) Saying RH doesn't provide any guide to root moisture sounds a little disingenuous to me; of course it does, doesn't it? It "may" not be the best (although I'd love to hear from anyone who has tried this, or at least logged RH% change throughout their misting cycle), but to say it doesn't provide "any" guide sounds silly.
3) Using your logic, we can still track RH% in the rootzone and adjust our feedings/cycle based off of that; i.e., by your logic when the mist has evaporated and RH% shoots up, (counterintuitively) that is when we would/should mist again.

I can track this in my structure, but we all know that my current structure isn't designed with HP aero in mind - that being said, if one of you wanted to measure RH% in your rootzone and how it fluctuates over your misting cycle, that'd be awesome to share with the rest of us.

Heck, it may stay constant at 95% or whatever, in which case my idea wouldn't work............but if there is a pattern it follows which corresponds to your misting pattern, then I do believe it can be used to our advantage.

Atomizer, would love to hear more of your thoughts on the subject, either good or bad.

Atomizer said:

Bete`s don`t come with adv`s but they should considering how expensive they are They`re not even available as an optional extra afaik.
Maybe you are thinking of Fogco nozzles, they offer 70psi and 145psi opening but like all adv`s the closing pressure is lower than the opening pressure.

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I was thinking of something like this, which won't even "operate" below 100PSI:

http://www.bete.com/products/mw.html

Of course I could be totally misinterpreting what that's saying, but I took that to mean that <100PSI nothing would come out of the nozzle.

They won`t generate mist worth a damn below that pressure but that won`t stop them putting out a line of water
Whether you get wet walls depends on a lot of things, temperature, humidity, misting duration and flowrate, droplet size range and even how well the chamber is insulated..a cold wall or lid is very prone to collecting condensation.
If you`d like to research using RH for mist control, a good starting point would be a search for "absolute humidity" and go from there.

I'm going to be using B-50 nozzles from hago, which are for oil heater atomizing. I found some independent research done that made me very skeptical about nozzle claims by manufacturers. It's a long read, but check out the charts starting on page 34 if nothing else. The droplet size can vary wildly depending on where the measurement is taken. Directly inline to the orifice it might have a sauter mean of 30 micron, but deviating from that it might be more like 100 micron. Where do you think manufacturers are going to measure for their in-house testing? In house testing presents a clear conflict of interest.

http://dspace.mit.edu/bitstream/handle/1721.1/9915/41995609.pdf?sequence=1

Hago also makes a nozzle with built in 90 psi ADV (hago 4023), but it's for insect repellent spraying and it has a very low flow rate and small orifice. Cheapest I've seen them is $10, but I'd need a lot of them and clogging will likely be an issue.

I tested some B-50 nozzles, and while they will dribble as the pressure comes down, the mist doesn't really suffer for it. The mist drops back pretty fast and then the nozzle gurgles down to zero pressure with a few drips. Since my nozzles aren't directly over the roots, it won't be a problem for me, so I'm going to try to use them as-is.

Both hago and delavan (competitor) make a separate ADV that attaches in place of the filter. for hago it's called the eco-valve and I can't remember the delavan one. They are expensive though, something around $12 each on top of the nozzle cost.

How well do those ADV's work? For $12 a piece I could just throw a solenoid right before every nozzle.

Other than the pain in the ass of hooking up and wiring 20 something solenoids, what would the benefit of an ADV be in that situation?

Atomizer, tried searching for meters that would measure absolute humidity but they don't make them............I appreciate your help, but I believe (hope) there's got to be a pattern in the RH% cycles inside the pods as related to the misting cycles.

Once (if) that pattern is found (will probably be different for each and every setup), then fine-tuning would be possible.

Bob Smith said:

How well do those ADV's work? For $12 a piece I could just throw a solenoid right before every nozzle.

Other than the pain in the ass of hooking up and wiring 20 something solenoids, what would the benefit of an ADV be in that situation?

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I would guess the ADV would work a little better for an instant cut-off. The valve is right at the nozzle intake. When I was testing my nozzles, the nozzle was right after the solenoid and I still got a drip or two out of it upon closing. The ADV would put a bit less wear and tear on the solenoid as well, as the pressure differential on each side would be less.

I don't own any ADV's, as the performance was good enough for me without them and I don't have the cash to spare yet. I'll probably try them eventually.

Anyone here have ADVs and can speak from experience? Sounds like ADV>solenoid for my purposes; one solenoid per pod (already have four), and one ADV per mister (so like 16 or 20 ADVs).

I`ve used/use netafim and fogco adv`s, all adv`s have an higher opening pressure and a lower closing pressure, the only thing that will open and close at the same pressure is a solenoid.

Atomizer said:

I`ve used/use netafim and fogco adv`s, all adv`s have an higher opening pressure and a lower closing pressure, the only thing that will open and close at the same pressure is a solenoid.

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So ignoring the hassle of wiring them all up (not a biggie), you'd go with a solenoid right in front of the mister as opposed to an ADV if given the choice?

Correction: the cheapest I've seen the 4023 nozzles is $7 here. Might be worth looking at if you add a few more nozzles to make up for the low flow of .75 GPH@160psi. I was considering them myself, but I wasn't running enough pressure for the ADV. It opens at 90psi. They disassemble for cleaning. As I've never used them, I have no idea how often cleaning would be needed though.

Those actually sound like a a great nozzle - super low flow (probably like 1/2GPH at 100PSI) and no flow under 90PSI? Plus being able to clean fairly easily?

"Winning"

Well, there's flow under 90 because, as atomizer pointed out, ADVs always close at a pressure less than their opening pressure. They open at 90 and close at something below that, probably 60-70 psi. I couldn't find any exact numbers on the closing pressure, but I do remember reading somewhere that they opened at 90. I'm sure it's plenty high enough to avoid large droplets. The nozzle is meant for spraying pesticides over living spaces and gardens without making a mess.

http://www.steamshop.com/4023antidrip.pdf

That's the only data sheet I could find. The only downside is that you may need to buy an adapter for the 9/16-24 machine thread. I lucked out and it just so happens the 9/16" threads itself into a 1/2" schedule 80 pipe It looks like some of those adapters have quick connects on them.

If you try them I'd like to hear how they work out I have the B-50, which is the same design with a higher flow and no ADV.