Im not sure where you are getting your information, but DO is entirely dependent on temperature, air pressure and salinity - nothing else.
No amount of aeration, injection, nano-bubbles or anything else can force extra oxygen - or C02 - into water.
This link has several charts:
Solubility of oxygen in equilibration with air in fresh water and seawater (salt water) - pressures ranging <i>1 - 4 bar abs</i>.
www.engineeringtoolbox.com
Discover the impact of dissolved gases in water purification and the additional need for consideration of their impact after purification treatment.
www.elgalabwater.com
At room temperature and sea level pressure - 1 BAR - you will not get more than about 9 mg/l or PPM - no matter what you do.
Even at 0 deg C, the max is still only just over 14 PPM, so I dont know where you saw 22 PPM for rain, but thats not possible unless the rain was getting pressurized somehow at altitude.
Also, when C02 dissolves in water it forms carbonic acid - which will drop your PH - because its an acid. This is even more dramatic with hard water and with some of the salts in our nutes.
You cannot force extra O2 or C02 into water over the natural equlibrium levels unless you use pressure - like C02 in soda. Open the can, and the pressure drops and the C02 fizzes out of solution.
Adding more nano bubbles, water falls, or any other type of aeration will only get you to that 9 PPM or so max DO depending on your water temp. Any extra you try to force in will just leave as fast as you try to add it. Its an equilibrium process and you cant change that.
C02 is the same way, except that it forms that unfortunate carbonic acid until it gets around to leaving the solution.
I get it and you are correct about co2 water. Co2 water is used becasue it is a more efficient process , better concentrations. Co2 water needs to be applied fairly quickly. As you can imagine co2 water is a great way to add co2 to plants you can't gas, outdoor. Yeah that acid is great for killing pests and mold, horrible stuff that would be even more horrible for companies selling pesticide. With high concentrations of o2 you can add co2 to the water and the roots will pick it up.
Yes, nano bubbles are just that. The science of nano bubbles are good enough for the US Army Corps of Engineers. They built one of the largest o2 generators using o2 or Speece cones.
https://balancingthebasin.armylive.dodlive.mil/2019/08/23/dissolved-oxygen-injection-system-a-remarkable-success/ Many different ways to apply o2 to water. Look up "o2 cones" and do some research if you want. This has been taught in many schools for quite some time so I would suggest doing your own research. I'm just a guy on the net.
Duration in water depends and if done correctly it can last 6 hours or more. In my mind the gains are worth it. Yes temp still applies and salinity as well. That 9mg/l usually requires RO water.
I use my dissolved o2 sensor and it confirms the results ( pic already provided with a temp on it). The speed that plants grew was great, better than the tote systems I had seen and built. My experience.
I respect your disbelief, I use tools I can see and touch they give me the numbers. I could be a negative Nelly and attack every idea but instead I spent the money, bought the tools, and got the answers for myself.
My motive is the lack of information available. I literally spent thousands and thousands building many different systems and digging through forum thread after thread trying to get the info. In the end I relearned some ideas and gained knowledge in others.
Rdwc and a chiller work great and grow fast, strong yield, totes. More work on the plants requires more man hours. market share is at risk.
Hydro Sog with heavy roots needs a flood and drain to force water movement and can be adapted to help wheelchair growers to grow for themselves.
NFT if done "perfectly" is slightly better than Rdwc in certain areas of growth, not yield, my 2cents. Might have been strain dependent.
Aero is best and I built low and high pressure with chambers as well. Every new system I have seen I have already built. Tray sandwiches to make a chamber, trys with a top( showed that pic), I have done almost every style. I have not done the wheel with the light in the middle. Aero also includes a Nft effect in its process and when you leave the res under the low or high Aero it adds a benefit. I didn't take anyone's word for it and spent time and money to prove it for myself.
I wish someone had provided this info so I had something to test against, try. I even tested cool air transfer over roots in a chamber with the low pressure water spraying. I was going to use a "o2 cone" and during that process I found Nano bubbles.
My goal was a system that was best for automation and reduced hours along with keep it simple. High pressure Aero killed the keep it simple part. Low pressure jets were able to manage even weak filtering for a full 3 months of continuous use. Mixing dwc and low pressure Aero with large sized jets was as simple as aero could get, still requires cleaning of jets and always checking. I did all of this quite some time ago. I have found many other people who have also done this in Aquaponics and so forth.
You dont have to believe me I'm ok with that. However if you are proven wrong please come back and share becasue this has been a pet peave of mine. As I searched for information I encountered many dead ends and very few answers. Lots of fighting with the desire to share "ability" or hold up ego, not information. If you prove anything I have said is wrong please share that too. I'm totally ok with learning, ego is not my deal.
Cheers
