Its kind of it like a 'Just-in-time' supply system for a retail store. You dont want to supply more 'stuff' than will fit on the shelves, because it just piles up and gets in the way. When that happens, the customers cant get what they want because all the excess 'stuff' is in the way. With the roots, too much water gets in the way of O2 delivery, and clogs things up.
At the same time, you dont want any empty shelf space with customers having to wait, and not getting what they want in a timely manner. With the roots, that means they starve for nutes and water even though they may be getting plenty of O2.
According to NASA, if you have a steady supply of 50 micron drops, the roots will have the perfect environment to up-take nutes, and O2 at the perfect rate for optimum growth. Any time spent too dry or too wet, is less than optimum for best growth.
The trick is finding that balance.
With the ideal nozzle, the droplets will be in the 20-80 micron size, with the bulk of them around 50 microns. At that size, you do get long enough hang times to be able to do Atomizers schedule, and maintain a reasonably constant supply of mist at a reasonably good level of 'wetness'. The math works in that case.
My nozzles dont come close to having that kind of hang time, which tells me the droplets are way too big on average.
You dont want them too small either - like with the ultrasonic foggers. They tend to produce 5 micron or so droplets, which float a loooong time. The problem is that 5 microns isnt "wet" enough. Its a dry fog. Plus the roots dont absorb that small a droplet as efficiently.
The problem is, if you cut the size of a droplet in half, the volume goes down by a factor of 8. The volume changes as the cube of the diameter. So a 50 micron droplet has 1000 times as much water as a 5 micron droplet.
There are a number of people who have been doing HPA for a good long while, so I am far from blazing any trails
However, there are a lot fewer of them than any other type of hydro. From what I have seen reading threads on several boards, most of them dont get even close to Atomizers goals. They may end up with very nice roots, and plants, but not fuzzy roots and drain to waste with out tooo much waste
The few who do seem to have it all together, seem to be a fairly secretive bunch, and dont like to share. Thats especially true of those doing Air Atomized Hydro. Thats something I just dont understand or agree with.
Atomizer does share a lot of info on the theory - as long as its not about specific equipment questions - especially nozzle questions. His posts are well written and dense with information, but often short on misc details, and context, which can be a challenge for a newbie, because he usually wont answer questions once he has posted something. Trying to push him beyond what ever he is in the mood to share just doesnt work. He only answers maybe one question in 5, so you really have to poor over his comments carefully.
I really like his theories and the ideas he presents. He is a wealth of information if you dig deep enough. I mainly wish he would share more equipment details, and not wait to tell someone they bought the wrong stuff until after its too damn late.