First HPA Cabinet grow

I use italtechnica PM12 pressure switches and caleffi pressure reducers, never had either let me down yet. I use a dedicated solenoid for each nozzle as the benefits far outweigh the cost of 4 solenoids.

If your root zone temps are above 68 you're going to have problems. Between that and the low humidity it would explain the wilting. I just finished my first aero grow and I ended up having to cool the root zone directly. Otherwise your roots will rot, among other problems.

Chamber temps upto low 70`s isnt muchh of an issue. The main problem is when the chamber temp starts to rise folks have tendency to increase the misting frequency instead of fixing the temp problem. The combination of the elevated temp and overwatering increases the risk of root rot.

These were subjected to high 70`s for a few days without any real drama. If the chamber temp is up there for a week you`ll tempt fate and thats never a good thing

Atomizer said:

These were subjected to high 70`s for a few days without any real drama. If the chamber temp is up there for a week you`ll tempt fate and thats never a good thing
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When are we gonna see the @Atomizer build thread so we can get the compilation sticky of all these unfinished builds that have no bud shots? Beautiful roots!

Its not that difficult, here`s a 60gal (220L) chamber equipped with a few hypro`s. The netpot is 80mm with the sides covered. A tad overmisted but healthy enough..you could say its in the pink

Just putting the finishing touches on a new root chamber. A little under 150 gallons.

I cool the root zone by chilling water with a thermo-electric cooler and then pumping it through this radiator and fan in the root zone. Nevermind the roots, they're supposed to be dead. This was between grows.

I've found that higher root zone temps translates to better bud to leaf ratios, but too warm leads to root rot. Having this climate control for the roots allows me to run much higher temps in the canopy without any problems with wilting.

Atomizer said:

Its not that difficult, here`s a 60gal (220L) chamber equipped with a few hypro`s. The netpot is 80mm with the sides covered. A tad overmisted but healthy enough..you could say its in the pink
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How many nozzles and what were the on/off times?

Covering the sides is a good idea. My first try I used 5" net pots and I had a lot of trouble getting clones started in them, since the sides dried out too much. This time I'm using these instead:

4 nozzles in that one. Timing varies from 1-2 sec on and 3 - 10 min off or more, depending on the growth stage, volume of rootage and time of day. Covering the sides encourages the roots down into the mist a bit quicker, you can always uncover them later on. The roots will stop at the covering so they`ll be sitting there ready to go out. It will help to retain moisture in the hydroton and prevent the mist from saturating RW if you happen to use that. Also helps to block light in the early stages, hydroton tends to have gaps that let some light through. No active cooling in this chamber just in the AA`s.

My last chamber was about the same size and also had 4 nozzles, but it was always super-wet and required excessive off times. I am still getting the hang of figuring out what timing to use to get root hairs. What do you guesstimate the timing was during that photo?

The goal is to get your off cycles as short as possible so you can squeeze in more cycles per day and thus more oxygen/nutrients. That's why I made my chamber bigger so it would dry out quicker. I may also put some vents or even fans that run for a few seconds at the very end of each cycle once the spray has already settled anyway. I tried it before but on all the time, and that seemed to impact growth too much so I stopped. But Stoner uses vertical upsidown-V shaped pods with wide-open sides and bottoms in a heavily ACed room instead. So opening up the pods for more evaporation and shorter spray intervals might be the way to go. I know that using fans allowed me to get away without a cooling system. I'd also like to experiment with using a giant smart-pot as the pod, and then just run a fan pointed at it whenever it overheats. Saves electricity on the thermo-cooler and is way cheaper. I was going to try it out outdoors this summer.

I'm just skipping hydroton altogether this time. It's not worth the hassle. Also, rockwool is a no-go, since it just sucks up the moisture from the spray and never lets it go again, so the roots rot right next to some hydroton where they're bone dry. It's just madness.

I'll stick with the PVC collars and pucks.

The longer on and shorter off are needed in the early stages when the roots dont have much area. The really long off times are only used at night. The ideal timing will need to be geared to the individual set up as theres too many variables between systems. The timing may be set at 1 second in a system but it could be misting for 4 seconds with the run on etc. Nozzle flowrate, placement and mist pattern whether solenoids and accumulator are used also plays a part.
The nozzles in the 60gal are solenoid/accumulator driven and create overlapping rings of mist similar to the olympic logo.
My large chambers use long throw, narrow cone nozzles that direct the mist pattern down the centerline. If i used those in the 60gal they would soak everything in the mist path and leave a lot of areas without mist. If i used the 60 gal nozzles in the big chambers they wouldnt have enough throw and i`d need more of them which increases the overall flow and they`d need a completely different timing schedule The rotary (syphon fed) AA creates a 360 degree doughnut pattern 5ft in diameter x 3"-24" high (adjustable). The pressure fed AA runs two opposing nozzles. The timing for both AA`s is different but the off timing in both is considerably shorter than for the hpa`s, typically a minute or less.

I just finished my pod and put some cuttings in it because I don't have any clones ready yet. The ones I took from the just-watered plant are looking fine. The ones from the one that wasn't at all wilted or dry but that I forgot to water thoroughly before I took cuttings are wilted now. I have it 0.5 seconds on and 4 minutes off. I think I may have to make it more wet, but for now it's just drain-to-towel, so I want to err on the dry side.

I've got 12 nozzles, 6 on each side. That's the max I can do on one solenoid. The pump kicks in right at the end of the 0.5 second cycle so the accumulator is pretty much maxed out for 12 nozzles at a time. I have 4 solenoids though so I could do 48 nozzles with this setup.

The 4 on the topmost holes that were watered well first are the HeadBand, then the 6 below that that are all wilted are the Afgooey x Blockhead that I forgot to water before I took cuttings. It was still pretty heavy and wet, but not wet enough obviously.

It's interesting because the topmost holes receive the least mist out of all of them.

I would use what ever timing you need to keep them upright at least until they have a reasonable amount of root. The timing setting is probably delivering more than 0.5 sec of mist so it may be enough.

I'm giving them a good 4-5 second soak any time I notice them drooping. Otherwise keeping them on 0.5 seconds

I was thinking of something along the lines of these pumps:

http://www.micropump.com/

There are lots of companies that make tiny little high pressure pumps like these.

I couldnt find a price but they look expensive and need an external drive. At the end of the day, the system will only be as good as the nozzles which produce the mist. The level of control will be limited by the hardware that has the slowest response time, in accumulator/solenoid driven hpa its typically the nozzles. The difference in cost between an all singing and dancing HPA and a basic AA is pretty negliable. The AA is less complex as it uses fewer parts (less plumbing) and offers a level of control you cant get with anything else. A pressure fed AA delivering 0.3 seconds of quality mist with zero run on.

Well, my last run was 0.25 seconds on time. So I definitely can do that.