Adventures in hydro #3 - AAA or Air Atomized Aeroponics - for sure!

[anon32470837]

I love my kitties, but they can be a challenge some times

The quiet compressor arrived today. So far, I am impressed. Its a lot quieter than I thought. I was worrying I would need to do something extraordinary to keep the noise down, but its less noisy than my old water pumps, so Im very happy.

The second Delavan nozzle will be here tomorrow. Ive been playing off and on with the one nozzle I have, and I seemed to be using a LOT more air than I calculated. I did some leak testing and found a very slow leak. but it was not enough to explain the rapid use Im seeing. Then it occurred to me to look at my math again. I was moderately stoned when I did it the first time.

Turns out I made a bit of an error. I did some of the conversions in my calculations based on cubic feet - but my tanks volume is in gallons! Duh!! So my math could be off by as much as a factor of 8. Im going to wait until I get things hooked up in their final arrangement and measure it

Im feeling pretty good about these nozzles. It would probably be better to have 3 or 4 of them, but I think I can make two work. That will help with the budget.

One the second nozzle arrives, it wont take long to get everything put together and functioning. Then I can do the final series of tests. That should only take a day or so. I have surgery scheduled for early next week, but I should have everything done by then.

I am really wanting to start a seed and play with the settings and see how it does - BUT - Im still trying to come up with a way to keep my rez cool. I think maybe part of my issues with the last grow was due to rez temps being too hi much of the time. That was in the fall when it was already much cooler than it is now. I can run the lights at night, so Im not too worried about the tent temps or the root chamber temps.

Im debating using an ice chest as the rez temporarily and just using bottles of frozen water for now. That will let me get started. Im on the search for a small, cheap, used mini-fridge. Im pretty sure I can rig up a chiller for a larger rez that way.

[anon32470837]

I made some good progress today. Got the second nozzle made up and mounted in the root chamber. I have one on each side of the chamber angled so that there is a slight swirling action. Its not as dramatic as my HPA cyclodropletron, but it seems to work well as far as distributing the mist.

I also got the compressor positioned where I want and routed all the air lines, mounted the regulator, and filter. Im using one of the 200 mesh ones from my HPA grow.

I also got the water lines, and valves all hooked up to a temporary ‘rez’ - just a 1/2 gallon jug for now. But thats when I ran into trouble. My solenoids that handled water at 115 PSI with zero issues, leave like crazy with just a couple of feet of head on the jug. Virtually no pressure at all. WTF?

I spent at least two hours swapping out solenoids, cleaning solenoids, etc, all to no avail. Then I noticed the label on the solenoid said the pressure range was 0.02- 0.8 MPA. Oh crap. These solenoids need a minimum amount of forward pressure or they wont seal. Actually, they seal just fine maybe 30% of the time, but leak like crazy the rest of the time. So I ordered the same solenoid in a 0.0 MPA version.

In the mean time that leaking doesnt stop me from running tests, and he new tests are looking really good. Im getting hang times and the mist quality that are much better than with the HPA nozzles - and thats with the root chamber still not 100% sealed up.

I finally found the cat lazer toy, so here is a new video. The camera is looking down through the hole for the 3" net pot, and the perspective is a little odd. When the red line gets to the center of the cut out hole, thats about even with where the the bottom of a 3" net pot would be - or about 2" down from th top. When the red line disappears at the bottom of the cut out for the net pot, the mist is still only 6" down from the top of the chamber. It takes well over 1 minute to settle that far, and well over 2 minutes to get down to the half way point in the chamber. That is much better than I ever got with the HPA setup. The mist is also thicker, and denser looking, so I know I have more smaller droplets than before. Once the chamber is fully sealed, those hang times should get even better.

I’ll be working on adding the extra air tank tomorrow and see about setting up some way to get accurate water flow numbers. The new solenoids are supposed to be delivered Sunday.

[anon32470837]

I just finished converting my 4.5 gallon water holding tank from the HPA setup to an air holding tank. It was pretty easy to do - drain all the water, let it dry out, and let the air out of the bladder. There is probably some dried algae still in the tank, but I dont care. All the air is filtered before getting to the regulator or nozzles.

By the way, the way these nozzles are made, there is no real worry about the water side of things getting plugged up. The water passages in the nozzles are about 1/8" at the smallest, so no small orifices to get plugged up. Im still going to filter the water as it leaves the rez, but thats mostly to keep clumps of algae or other small debris, bugs, etc, that may get into the rez, from getting to the roots.

The air passages on the nozzles on the other hand are very small, so the filter on the air side is important. I am reusing my 200 mesh filters from the HPA for this as well. Fortunately, I bought filters that can handle hi pressures.

Im running some time trials at 5 PSI now to see how often the air compressor is going to cycle. Its clear already that my math was seriously far off when I did the original calculations. Its going to be a few hours at most between compressor cycles rather than the day or more I originally calculated. It seems Im not very good at math when Im stoned

The trade off when using a larger air tank is that the compressor takes longer to fill the tank. I changed the settings on the pressure cut off switch on the compressor. The default was a cut ON of 90 PSI and a cut OFF at 115 PSI. I Lowered the cut ON pressure down to 60 PSI. Thats the lowest the switch would go. With those settings and the added 4.5 gal tank, it takes the compressor about 2 minutes to re-fill from 60 PSI to 115 PSI.

I was a little worried the nozzles would be annoyingly loud, but it looks like Im going to be fine keeping the pressure down at 5 PSI to maybe 7 PSI max, and they are not loud or annoying at all at those pressures.

I’ve been monitoring the root chamber temps while Im running these tests, and depending on the cycle times, the root chamber is staying a minimum of 6 degrees colder than room temp to as much as 8.5 degrees colder when Im running very short off times. Thats with a room temp at 73.5F and the water in the rez is at 73.1 F. Im going to try adding a fan inside the foam enclosure to see if that makes any difference.

Once new new solenoids get here, and I get the run-on dripping at the nozzles fixed, I’ll be ready to grow!

I decided to give it a try even though this is the middle of summer. Im not too worried about temps in the tent. I can run the lights at night to help with that. Its looking like the root chamber wont be a problem unless the temps get really bad. My main concern is the rez water temps. On really hot days, my room temp climbs into the upper 70’s to lower 80’s. Im going to try with a small 5 gallon rez set inside an ice chest and see if frozen water bottles will keep thing under control well enough. I suspect Im going to need to run a sterile rez, but Im hoping not. It just bothers me to shoot bleach at roots. I would try bennies too, but so far they have done nothing for me.

Anyway, I still have some unknown seeds left over from my disaster last year, so I started soaking two of them for a test run. Im going to try two plants this time instead of the single plant I did last time. The yield from that single plant was really really good in the HPA setup, but it takes twice as long to fill a scrog screen with one plant than with two plants. Im hoping a faster veg cycle will help reduce problems down the road. If nothing else, maybe the root balls will stay a more manageable size and not totally crowd the chamber like they did last time.

It will likely be at least a week or two before the new test victims are large enough to put in the AA system. Once they crack in the paper towels, I will put them into small dixie cup ‘Hempy buckets’ until they are 2 or three inches tall.

[anon32470837]

The two “zero MPA” solenoids arrived today, but one of them leaked just as badly as the old 0.2 MPA solenoids. Grrrrrrrr. After some more swapping out of solenoids, I dont think it matters which ones are used. Some of them just leak and some dont. After going through three more of my old ones, I found one more that doesnt leak water or air.

So, I now have a zero leak system.

I just finished a series of flow tests for air and water.

The water side is looking good. The two nozzles together have a liquid flow rate that varies from 3.6 ML/second at 4 PSI, down to 3.45 ML/second at 7 PSI. That is a much higher flow rate than the delavan spec shows, but thats because I have positive pressure with a gravity feed rather than the nozzle having to siphon the liquid up against gravity.

For comparison, 4ea of my old HPA nozzles had a total flow rate of 3.22 ML/second. So two of these Delavans, with the gravity feed the way I have it now (aprox 27" of ‘head’ height) have about 10% higher flow rate at 3.6 ML/sec. One odd thing is the flow rate seems to go down slightly as the pressure goes up. Thats the exact opposite of what Delavan shows. Not sure whats going on with that.

On the air side, with my 5.5 gallons of tank storage, I am getting 90ea 1 second cycles, at 6PSI, before the compressor kicks in and refills the tank. Thats a lot less than I was originally thinking I would get. If I end up at somewhere close to the same cycle times I had before - 0.7 seconds ON and averaging 60 seconds of off, that works out to the compressor cycling ON roughly every two hours for two minutes. If I run at 5 PSI, or 7 PSI, those times will go up or down accordingly. I can live with that, but I was hoping for much more time between the compressor cycles. Down the road I will probably add additional storage tank.

Both of the seeds popped in the paper towels and are now in mini hempy buckets.

While I wait for them to get a couple of inches tall, I will be working on cooling the rez…

[anon32470837]

They are off to a good start! Should only be a few days till they are tall enough to put in the AA system.

I found an old ice chest in the garage, so Im going to try using it for a rez with frozen water bottles and see how that goes. It only holds 9 gallons, but thats plenty for now. Still looking for a cheap mini fridge, but no luck so far.

[anon32470837]

Its official! Im now growing using Air Atomized Aeroponics!

The two test subjects had about 2" of stem showing in the mini hempy buckets, so I stuck them in the torture chamber. We will see how they do…

First, the ice chest is working great so far for keeping my rez water cool. Right now, our temps are not that bad, so will have to wait and see how much trouble this is on a series of really warm days. For now, a single frozen 16oz water bottle drops the temp in the chest down to the mid 60’s range from the low 70’s. It will stay below 70 all day.

Im starting out with 0.4 seconds ON and 25 seconds OFF, and I adjusted the nozzles so they spray directly at the net pots. I want to be sure they stay nice and wet while they are getting used to this new environment. I set the PH to 5.8 and the EC is at 0.4 to start.

They have been in there for about two hours and are looking just fine so far…

[anon32470837]

I up-dated the spreadsheet I use to calculate flow rates based on ON and OFF times, etc. I added a column for compressor cycle time and made some minor changes for the new root chamber size. Its now 51.4 gallons total volume.

Change the extension from PDF to XLSX

AAAflowrate.pdf (12.9 KB)

The babies still look good. Timing is still 0.4 ON but Im up to 35 sec OFF. The roots are starting to grow some, but I have not been able to get a decent pic yet…

[Northern_Loki]

How’s the PH looking at this early stage?

[anon32470837]

@Northern_Loki

How’s the PH looking at this early stage?

Interesting you asked that - Iwas just about to post on how that was going

So far - 24 hours - its holding perfectly at the initial set point = 5.8.

There are several things Im doing differently this time around which I hope will keep things that way and avoid the wild PH swings I had last time.

1. My light discipline is much much better. This ice chest is pretty much perfectly light tight, but Im also draping it with a blanket. Im careful to not leave the lid open for longer than absolutely necessary. I also wrapped the fittings, and feed line that exits the rez and runs to the root chamber with aluminum foil for the full length.

2. Im only stirring the rez for 1 minute every 8 hours. So far though, agitation alone does NOT seem to be raising the PH. I checked PH when I filled the rez and added Mega Crop. Then I let the pump run for almost an hour. I did that partly to see how much heating occurred in the water from the pump running (its very little), and also to see what the PH did. I suspect that the algae that was growing last time had a lot to do with the PH going up every time I agitated the water.

3. Im managing to keep the rez well under 70F. The highest temp Ive seen so far is 68F. Thats after cooling it down to around 65 yesterday with a single 16oz frozen bottle of water. So its only gone up 3 deg in 24 hours with no ice. The water in the feed line to the root chamber does warm up some. It is running 2 to 3 deg warmer by the time it enters the chamber, but Im not worried about that. Any bugs or algae wont stay in the tubing long enough to get frisky.

Which brings me to the next interesting and unexpected thing I found today - Im going to have to hook up the heater in the root chamber! Its actually staying toooo cold.

The last couple of days, my grow room temps have been staying in the low 70’s. 72F to 74F. With the cool water feeding in, and the short cycle times, the root chamber is staying in the 65 to 66 deg range. Thats just a bit too cold for my liking. A little warmer will help with root growth and still not risk root rot growing.

So far, everything seems to be running smoothly. The lights are due to turn ON at 6PM. I will be checking everything carefully then.

[anon32470837]

Everything looks good so far. The roots are growing on both plants and are staying nice and wet. No sign of fuzzy hairs so far, but its still early. I think it will take a few days for them to start showing up, but only after I get the mist timing dialed in better. Still too wet I think.

Based on the too wet thing, I have changed the timing from 0.4 ON / 40 OFF to 0.3 ON / 30 OFF. That is the same exact flow rate as far as the water and air, but the shorter cycle should be better as far as maintaining a uniform environment. The goal as always is to avoid a wet/dry cycle in favor of a more uniform dampness with the correct size droplets. At this point, Im not worrying about ‘filling the chamber with mist’. I just want wet roots so they dont dry out.

Here is a screen shot from the spread sheet showing various settings and how the flow rates, times, etc vary.

Here are the roots this evening.

I dont think I posted any pics of the nozzle installation. They are positioned at the bottom of the root chamber. I mounted each nozzle to a plastic lid, then put a screw through the lid into a PVC ‘T’. That screw allows the lid/nozzle to rotate on the vertical plain. The PVC T is not glued onto the PVC pipe its hanging from, so the PVC T allows the nozzle to be rotated horizontally as needed. The T can b e raised or lowered in the chamber by cutting the PVC pipe shorter as needed. The pipes can also swing back and forth to a small degree to allow for another degree of adjustment for aiming the mist. Almost all of this is just hot glued together. I dont think you could do it much cheaper or uglier

[anon32470837]

I got a couple of pics with the USB scope. No fuzzie hairs, but some small bumps here and there that look like possibilities, maybe.

[anon32470837]

I got some better root pics this morning. They are developing fast! The second pics looks like some fuzzies are starting to show up on the laterals

[anon32470837]

I finally collected enough runoff water to check PH and EC.

The EC in the rez is 0.3. The runoff is 0.4. Im sure virtually all of that increase is due to evaporation.

The PH in the rez is still holding at 5.8 with zero change at all so far. The runoff was at 6.7!!!

Im still not at all sure when the PH change occurs. Is it as soon as the water leaves the nozzle or not until some time later? Is the water somehow changing for some other reason than the spray action?

Im going to have to think of some way to test this, but Im not at all sure how to even begin to measure the PH of a 50 micron sized droplet.

On the plus side - the roots continue to develop more laterals with fuzzy hairs! Its still not much, but things are moving in the correct direction.

[anon32470837]

Ive been trying various ways to collect and test the PH of my water after is leaves the nozzles. So far all Im certain of is that the PH goes up after it leaves the nozzles. From 5.8 to 6.7 on average.

So I did some more tests with tap water to see how agitation effects its PH. My tap water starts at 6.7 these days. After putting a cup of tap in a mason jar it tests 6.7 initially. After shaking the vigorously for about 30 seconds with the lid on, the water reads 7.0 to 7.1. My tap EC is under 0.1.

Then I checked a sample of the rez water the same way. It starts at 5.8 with an EC of 0.3. After the same vigorous shaking, it reads anywhere from 6.4 to 6.6.

So, my tap water goes up about 0.3 to 0.4 when hand agitated.

The Mega crop rez water goes up about 0.6 to 0.8 when hand agitated.

The same rez water goes up 0.9 when sprayed out of a nozzle.

The one slightly positive thing is that the change seems to take a while to occur. There is a fast initial change of a couple of tenths of PH rise. That seems to happen by the time I get the meter back in the test solution. The full increase seems to take at least 3 minutes or maybe longer to finally settle down.

I hope that means that maybe my roots are seeing water that is still close to the correct PH. On the other hand, if this process is based on the O2 in solution or is the result of aeration, then all bets are off. The micron sized droplets should reach max dissolved oxygen levels very very rapidly due to the hi surface area to volume ratios.

Oddly though, I have a 300 GPH pump in the rez that turns on and stirs the water for one minute every 8 hours. That level of agitation/aeration has not change the PH at all over the several days the rez has been running.
So, mild agitation and aeration dont seem to do anything.

In other words, I still dont know anything other than that the PH goes UP when I spray.

[Northern_Loki]

Super interesting. Need to think about this for awhile.

Initial thought that I do wonder about is the gas dissolution, does the PH for the various trials drop back down to the original value after being allowed to sit for awhile?

I can’t quite recall but I ran into an issue with the DO tests when looking at tap water in this manner. PH straight out of the tap, if that’s the case, may be misleading. I think this needs to be allowed to outgas/stabilize to the surroundings for a period of time prior to using it for a test. The water system is under pressure and, if there is any gas around, it will have a different partial pressure resulting in a different rate in solution. And, I’m thinking if it’s CO2 in solution, the initial PH could change as the gas either outgasses or dissolves into the solution due to the different partial pressures (temperature affects this, too).

The process is not “instantaneous” as a volume. Although, coming out of a nozzle as a mist, there must be a huge step change in pressure (the why to why it’s misting) and, as you’ve noted, a relatively fast outgassing until the partial pressures of the dissolved gasses stabilize.

pH of Water with dissolved Carbon Dioxide and Calcium

I don’t think O2 will show a significant effect on PH. CO2 on the otherhand will. And, the alkalinity of the solution + CO2 will indicate PH. Both gasses are in the atmosphere so you’ll have both in solution. At different rates depending on the temperature, pressure. Then, add alkalinity to determine PH.

This is a bit much, but “Mathematics of the total alkalinity–pH equation” gmd-6-1367-2013.pdf (1.6 MB)

[anon32470837]

Ah! Thanks for the reminder about CO2 and alkalinity. Im still not 100% on the whole alkalinity thing. For some reason, it just doesnt stick in my head.

Your comments also made me think of other things going on when the water gets atomized.

1. As you say, there is a big pressure change with HPA - from 100 PSI to zero in an instant. In the case with AAA, Im using gravity feed on the water side, so virtually no pressure change there, but there is still a huge shear force when the air hits the water as it leaves the nozzle. I suspect that is acting similarly to how a pressure change would.

2. there is also an abrupt temperature change. As the droplets leave the nozzle, there is an abrupt drop in temperature of the droplets due to evaporation. Thats the effect thats forcing me to heat the root chamber even in summer.

The water in my rez is currently sitting at around 65 degrees. It travels through tubing and warms up to the low 70’s by the time it reaches the nozzles. Then it almost instantly drops down to the low to mid 60’s again as the droplets evaporate inside the chamber.

With the HPA setup, the water started warm, and just did the one temperature drop, as opposed to starting cold, then warming, then cooling again.

As the water mist cools, the dissolved CO2 levels should increase, so my droplets should be increasing in dissolved CO2 - BUT that should LOWER the PH instead of raising it.

The other thing that is happening is the the EC is increasing as the droplets evaporate. That should be increasing the alkalinity also? Im not at all sure how that would affect PH though.

So far I have not seen much if any drop in PH over time, but I have not really monitored that rigorously or for more than a few minutes. I will do that today.

Very interesting indeed. I would enjoy it more of I knew for sure if this was actually affecting the plant growth or if its just a curiosity of no real consequence.

[anon32470837]

Another second thought - you’re right about the tap water and probable extra CO2 from pressure in the system. I did not give it time to stabilize. However, the rez water has been in the rez for several days, so Im sure it has had time to equalize the partial pressures of CO2 and O2. Yet tap water and rez water both go up in PH when shaken - the rez water more so. In those shaking tests, there is no abrupt temperature change or pressure change, and I dont see how shaking would change the alkalinity, so Im still mystified.

[Northern_Loki]

[anon32470837]

You are THE MAN!!!

From that video, its the turbulence from the bubbles thats causing the CO2 to leave the solution. That would be the same effect when shaking the water and especially when spraying the water. The shear forces that break the water down into small droplets have to be many times as strong as simple bubbling.

So, in my original HPA rez, I was running the pump far more often and for longer times than I am now. I also had it set up to flume much more strongly. That frequent fluming, plus maybe the algae that was growing, could easily have been why the HPA rez would increase PH.

Then when it got sprayed, the shear forces, and probably the sudden increase in surface area when the droplets get formed, would drive the PH up even more.

With the new AAA rez, Im doing very little stirring/fluming at all - one minute every 8 hours vrs the old system at 15 minutes every hour or so. Im guessing the new setup might be raising the PH slightly when the pump runs, but then the water has 8 hours to re-equlaize the CO2 in solution.

Both HPA and AAA nozzles will cause vastly more ‘turbulence’ and aeration as the droplets get formed than a simple air stone.

Ok, so that explains whats happening - but - I still have questions.

1. Does this really matter? Or to put it another way - am I worrying about a phantom problem? Is the PH rising as the water leaves the nozzles really causing the plants any distress? Or is the water still within range as far as PH by the time the water gets to the roots?

It seems to me that every single HPA and AAA setup that uses hi pressure water or air to atomize water would have the same exact problem of the PH rising. I would also expect LPA systems to have the same problem of a climbing PH. Especially in re-circulating systems, but maybe to a lessor degree.

Its common for recirculating systems to have PH issues, but its hard to know what the exact cause is in many situations. It really makes me wonder though.

I would expect ALL HPA and AA setups to have the same problem, especially if they are recirculating, but no one has called it out that I have seen.

From that video it looks like a slow process, but I bet that micron sized droplets would react much faster than a larger water volume.

It would be helpful if I could test the PH of the water as soon as it leaves the nozzles, but it takes hours to collect enough volume to read with my PH meter.

So far my only idea is wait to see if the plant tells me its having issues related to PH and adjust accordingly. In the HPA grow I did try lowering the PH in the rez to adjust for the PH changes, but that didnt go well. I may have over corrected, but I just don tknow.

In any case, thanks again for finding that video. Its a big relief to finally have a theory for whats happening that makes sense AND fits all the data and observations!!

[anon32470837]

I decided to try something as far as testing the spray PH. I have some pool/spa water test strips that check alkalinity, PH, chlorine. I got them to test chlorine, but they dont work for crap doing that. I decided it wouldnt hurt to try the PH test and see what happens.

Unfortunately, they only go from 6.2 up to 8.4. When I check the rez, which is still at 5.8, they show the lightest color which is 6.2.

So I tried several of them by holding them in the spray coming from the nozzle at different distances. They all read the same - the minimum of 6.2.

Then I put one in the runoff water (which takes several hours to accumulate) and it immediately turned darker and indicated the PH was around 6.8 - which is close to the 6.7 I measured with my meter.

So…if these strips are reading correctly… it looks like the water is not changing PH instantly after leaving the nozzle. After maybe 3 minutes, the strip is noticeably darker, but stil not as dark as the test from the runoff.

If thats what is really going on, and not an artifact of defective test strips, then thats good news. It means that the roots are not getting blasted by hi PH water. The roots that eventually make it to the bottom of the root chamber may have issues, but that is only going to affect a small portion of the total root mass. I am more hopeful now.

The top strip is from the rez. The middle ones are all from various distances away from the nozzles. The bottom strip is from the runoff water.

On the bad side - Ive been loosing root hairs since yesterday. I have been forgetting to keep my bottle of LITFA handy, and so I have been unable to resist the temptaion to mess with timing. Im going back to my original 0.3/30 and see if they come back.