Oh, I’m really sorry, I didn’t read carefully enough and missed that you’ve said about aeroponic system in space. But to be honest I think that periodically spraying with force (like HPA and even AAA) will give enough momentum to make particles floating around: it’s a kind of replacement for fans. If you check my tests videos I’ve put earlier you’ll notice that mist never become still, it is always in motion. I assume the same has to happened in space with the only difference that particles aren’t going to fall down.
But from the other side if mist doesn’t go away via falling it might mean that it requires even less misting cycles and in that case it would probably necessary to have some kind of air mixing. Good point.
Not sure if we are talking about the same or different things
From my understanding aeroponic doesn’t allow roots to have all their surfaces covered by nutrients and it is one of the advantages. “True” aeroponic make roots to be covered with very small particles, but they doesn’t coalesce so have enough gaps to supply O2 from the air around. IIRC one of the rules is if small drops on roots merge to bigger ones it means you are overmisting and/or drops diameter is too big.
Im not up to a full response on all the things posted so far, but here are some random thoughts in no special order.
I was sure I saw a reference to the aeroponic experiments being done on the MIR - maybe. Im not sure it really matters though. It looks like Stoner was pushing the 5-50 or 20-100 droplet sizes on his own. I think I saw at least two different size ranges in different places though - over lapping and ranging from 5 microns to at least 80 over all.
Again Im not sure it really matters that much because we cant measure our droplets. All we can do is see how long the smallest ones “hang” and hope for the rest to follow.
For the HPA hydro nozzles, there is some SMD data/charts available for some of the stainiless and brass nozzles, so you can get a start from there if thats the way you want to go. I forget where I found those for sure. If you want, I can look for the references/links.
The HPA nozzles I used did seem to produce some good results. I had huge fuzzy root balls.
The difference between HPA vrs AAA is the complexity of the system, and the range of adjustment. AAA has a lower part count, plus a greater ability to choose different flow rates and droplet sizes as needed to respond to what the roots are doing. With HPA you can only control pressure. That changes the flow rate as well as the droplet size. With AAA you can adjust them independently to at least some degree, but more importantly, you have a much wider range to choose from with a single nozzle. You can vary both the water pressure or siphon height as well as the air pressure.
HPA has much cheaper nozzles, and a lower cost over all to setup. But AAA - other than the nozzles - is very close to the same cost, with a lower parts count.
AAA also can give you a much better mist quality easier than you can achieve with HPA. Unless you can position your solenoids very close to the nozzles, and have one solenoid per each nozzle, and use an accumulator tank, and a pressure reducer, and nozzles with antidrip valves (that work), you will have lots more run-on spray and large over size droplets.
The Delavan AAA nozzles Im using work ok, but have room for improvement. I think mine produce droplets that are over all too large on average. The SMD or MVD is higher than ideal - I think. Still, they do work. I have some pretty nice root balls at the moment. I will be posting more root pics shortly in my thread.
As far as spraying the roots directly - there was one reference in one of those links about it being necessary to spray the roots directly in order to insure the mist penetrated into the root mass. I think it was in the same place they had the mist running for 12 seconds ON and 40 seconds OFF. I just cant see that working to produce fuzzy roots. way too long an ON time mainly.
I also dont buy the roots being physically damaged by direct spray. Maybe if you were running 200 PSI or something with HPA, but I have seen no evidence of physical damage with HPA or AAA, and I have directly sprayed roots in both cases. Its impossible NOT to do it in any reasonable sized root chamber. Roots will grow directly into and completely over grow a nozzle if they can reach it - with beautiful looking roots the whole time.
This root ball is 24" in diameter and extends all the way down to the bottom of the chamber 29". You can see where the nozzles are being swallowed and the roots are loving it. I used extensions, elbows, swivels, etc to keep moving the nozzles to different places, but the roots won that battle.
By the way, there are lots of options with HPA nozzles to get below well 50 uM droplets. I had some excellent hang times - plus 2 minutes which has to be below 20 microns.
I am more and more intrigued by the idea of using disks to generate the mist. There are several challenges for DIY building though. The top three are balancing the disk mechanism unless you use a commercial disk. Even then, if you use an extension shaft, that can introduce balance issues. Then there is the problem of cooling the motor without letting it get wet. I have some ideas but it will take a lot of trial and error playing around I suspect. We might have to consider the motors an expendable item that will need replacement at intervals.
I recall people using TeeJet nozzles in grows. It seems like they had some success, but I dont recall the exact model numbers. They are cheap enough to play with if you have the HPA setup already. The stainless nozzles I was using cost about $5 ea, plus an other $5 or so for ADV’s, and about that much for the swivels. You will need to do good filtration no mater what HPA nozzles you use to keep them from clogging. IIRC, mine were around 0.5mm orifice.
As @heathen said - you need to think of the mist as a growing medium rather than just a way to spray the roots. Its not really like NFT, but it sort of is as far as the end goal.
With NFT and HPA and AAA, you are trying to create a super thin layer of water on the roots. The reason for that is that water is sloooow to transfer oxygen through thick layers. Very thin layers on the other hand reach max dissolved oxygen levels very rapidly. The key being very thin layers.
NFT relies on surface tension to wick the water where it needs to go. That water that is wicking via surface tension is going to be very thin which allows for good oxygenation. The water supply needs to be minimal thickness to work well, so it doesnt over wet the roots. Too thick a layer of water will reduce the oxygen the roots can get, and most NFT systems really do over wet the roots. The perfect NFT is a membrane meniscus system, but it has technical issues of its own - mainly the membrane is a bitch to get right.
HPA and AAA try to achieve that same super thin layer of water by spraying micro sized droplets. Those micro size droplets will reach max dissolved oxygen very rapidly even if the water didnt start out with enough oxygen. The trick there is to not over spray and create too thick a layer of water. Thick layers wont have the same oxygen to start, and will slow the transfer of O2 from the surrounding air.
The related problem is direct spray - it will almost always over wet the roots and prevent the fuzzy hairs. With too much water, the roots dont need to grow the fuzzies. They just stay as smooth hydro roots. Thats not BAD, its just less than ideal.
You can get fuzzy roots when you direct spray though. You just need to use very short ON times and longer OFF times. Again, the goal or trick is to not over wet the roots and give them enough time to dry out.
Better yet is to generate a perfect mist environment that doesnt over wet the roots and deosnt require them to dry out from excess water. Thats the elusive goal is aero.
When I post the root pics I will have more comments on this whole thing in my thread. Maybe tomorrow if Im feeling better.
I think thats just going to make everything too complex. Plus, Ive already talked about direct spray. The moisture they need to keep from drying out needs to have the same nutrients. If the water droplet is on the root, they are drinking it, and will want the nutes.
Good point. I think it would be much easier to get to the ideal mist environment in space. We have to deal with gravity.
Yeah, its a balancing act. Ive found you need to have some accumulation of droplets or the rots just grow sideways towards the nozzles, but too much means not fuzzies. I have never had perfect 100% fuzzy roots. There are always some places where they stay smooth, some places where the air prune, and you get fuzzies other places. Thats because its not easy to produce that uniform environment from top to bottom in the chamber and on all sides of the root mass - especially as it gets bigger and starts to fill the chamber.
Thats why having enough nozzles for good coverage of the root mass is one of Atomizers items to consider when designing the system. You have to balance having enough nozzles to really cover the entire root mass with out having too much flow so that the roots stay too wet. This is where “filling the chamber with mist” comes in. Its also why it helps a lot if you can have a wide range of possible flow rates with your nozzles. As you add more nozzles, you need to lower the flow rate of each nozzle. Fewer nozzles, and you need to increase the flow rate.
BUT - with fewer nozzles, and higher flow rate, it becomes more difficult to not over wet the roots with direct spray. With too many nozzles, its hard to get the over all flow rate low enough.
Interesting, I guess I should have assumed that people experimenting with this stuff would have already thought of that haha. Do people with these systems generally use some type of wetting agent to break up surface tension of the water? SM99 might be useful, it’s also good just to keep hydro systems clean…lines etc
Thats a very good question that I have also wondered about. I have seen a few other people ask the same question, but have not seen anyone post any real answers or results they say were due to wetting agents.
Some of the soil guys seem to think they are good, and they are used in agriculture to some degree.
It might be worth experimenting with at some point.
Just doing the thought experiment in my mind, I cant decide if having the tiny droplets bead up (no wetting agent) or spreading out more when they hit a root (with wetting agent) would be better or worse. I dont know about SM99, but some wetting agents cause foaming. That would be bad I think, but low concentrations might be fine.
If I had some on hand I would be willing to try it, but I havent been curious enough to invest in some.
Haven’t heard about using any wetting agents before. You live and learn
But I’m not sure it is useful with aero. I thought that roots should be covered with drops and not with water\nutrients film. But of course it worth trying. The only problem it requires a dedicated chamber to have a control group without wetting agent and a test one with such agent.
And another concern is its composition: aren’t they toxic? And quick googling shows that they use in conjunction with pest control mixes but I didn’t find any mentions on using it for watering
They key here would be how thick the film was. The NFT theory is based on thin films being able to reach max dissolved oxygen really easily and fast. If the film stayed as thin as the droplets are in diameter or close, then I would expect similar oxygen levels.
However, I know roots can take in oxygen directly from the air - no water needed. The question is whether the film would transfer more or less oxygen than droplets plus direct contact with the air.
I have no clue, but I doubt its a big difference either way. Properly done NFT or membrane meniscus is very efficient at oxygenation.
Surficants are used where the soil is difficult to “wet” for what ever reason. That makes the soil subject to rapid drying out because it cant hold as much water - it drains right through the soil without clinging to the surfaces of the particles in the soil. The ones intended for growing are safe - I guess
I’m not sure to be honest. Sm90 (not 99 lol) is made from coriander I believe and smells amazing.
I used to use it in a small store bought aero system, nothing like yours just the mainstream style with tubes and mister heads. The sm90 seemed to really help keep lines and stuff clean and the plants definitely loved it. I used to use for all plants until I couldn’t find it anymore.
A few drops of dish soap can work as a wetting agent too, I don’t think there’s any risk of toxicity from it?
They actually really do. My gramps used to drain his washing machine into a tub outside and would water his garden with it. You would think detergent would be too much but it worked great…not sure of the safety of it but he lived to be almost 100 lol. Dish soap is of course non toxic.
LOL I remember my grandmother taking the wash water out and dumping it in the garden. I also remember my grandfather saying you never do that with the worm bin because it will drown the worms.
If I wasnt in the middle of changing several variables already I would be very tempted to try a few drops of dish soap in my system. I may do that just before harvest just to see if the roots react in any way. I could add a drop or two to my small siphon tank so I dont risk the entire rez…
As far as a safe surficant - I think yucca would be a safe bet. I know several soil growers who use it. I think @ReikoX?
There is a difference between detergent and soap. Real soap is made with oil and lye. Get something like Dr. Bronner’s Castile soap. Detergent is made with petro chemicals.
Oh oh! I forgot about that. I sure dont want any organics sitting around in my rez or siphon tank.
Hmmmm. I have Potassium Hydroxide/lye on hand - BUT - I use it as a PH UP. It would drastically change my PH. I could adjust it to PH 5.8, with phosphoric acid, but Im dubious.
Ok, after 5 minutes of Googling Im now thoroughly confused on exactly what is or is not a surficant and if lye is or isnt all by itself or if it changes when you adjust the PH or if you need the oil or??? LOL!!
Potassium Hydroxide (really any aqueous base) reacts with oils and heat in a chemical process called saponification. The result is soap and alcohols if memory serves.
Let me clarify that a bit, I should say it is approved for organic gardening. It doesnt have any humic acids or sugars in it that will promote microbial growth. When was the last time you saw mold on a bar of soap?
