Oh dear I spent a good bit of time responding, but it did not upload.
MM, First I will answer your question about how my plants are responding to increased mist times (now 15-30 seconds to 30-40 minutes) GREAT.
Not that evolving F&D was considered beforehand, but I think it was A who stated this, and it got me thinking. Decades ago, I grew huge trees with F & D, so I understood what he was suggesting. Where what I am doing now differs in that is, instead of feeding ~ every 4 hours with some nutes and DO remaining in the medium, my shorter feed cycles and high pressure nute delivery compensates for not having any medium to hold some of the nutes and oxygen between feed cycles. And as we know, atomized nutes are more readily absorbed. I will be posting pics of my new plants and my lonely lady (above and below) on my threads and journals here and elsewhere.
As to having BobS' back. I like him. He has the passion, desire and interest to push the envelop and apparently has the money to toss his mistakes. If you see his last HPA effort, the coliseum, you will know he is "learning". Now it can still be used for cloning or growing short root veggies. If you look through his thread you will see I told him why that wouldn’t work for mj roots. He now realizes what I, and probably others, were saying about this.
When it comes to TAG and HPA, basically we all are gleaning information from others and adapting it to our abilities and resources. We start with the information available at that time, which over time may turn out to be bad information, or the result of not fully understanding the method and even the hardware that was available at the time, like Pod Racers TAG. The pods they were building near the end are very serviceable today, though round pods makes it easier for the pressurized nutes to swirl throughout the pod. The primary purpose of the pod is to provide ample depth and area around the roots to allow for nutes to swirl and drain.
Let's get to the point I have been trying to get BobS, specifically, but anyone building a Pod to understand: using a silk screen to keep roots longer than the pod depth from reaching the bottom of a short pod. If it’s just a few inches no problem, but think about how big a ~ 3-4ft mass of HPA roots is. (5 ft tree= 5 ft roots; 2 X 2 X 2 ft pod with screen in place leaves ~ 20” above the screen to retain the mass. Why do I consider using a screen in this scenario problematic?
No one here will dispute that roots grow like crazy in HPA, when delivering nutes via an accumulator, probably more so. My last journal (on another site) I was using bag seed that turned out to be Sat dominant. Just as the plants quickly outgrew the space between the ceiling and the light, the roots quickly outgrew the 17” of pod depth. I had to add a second stacked tote (cut the bottom of one and the top of the other) to handle the 4 ft long roots that developed from 4 ft plants.
I was in mid flower and was recirculating nutes. One of my mentors made me aware that from mid flower on, the plant hormones change radically in support of massive bud development. He suggested I consider D2W, and to test my runoff. At first, I didn’t believe it would be ‘that’ big a deal, so it took me a few days before my curiosity got the better of me. WOW. My feed ppm was 900-1000, but my runoff was over 2000, with similar pH increases. Most likely BobS’s mentor's are using D2W, but that won’t solve the problem a shallow pod presents. Let's look at it logically...
If you are growing a 5ft tree in a 2 ft deep pod, you will quickly wind up with ~ 3ft of roots accumulating on the screen, that by mid flower double or triple in mass. Now that mass has to go somewhere. If it is allowed to stack on a screen it will spread, quickly covering the entire screen and even turning and growing up the sidewalls, but most of that mass will stay on the screen. This root mass will be roughly 6-8" thick, and though the root mass is fluffy, the runoff (both from the roots above the mass itself) is slowed down by the mass it has to drain through. Some portion of this runoff will be reabsorbed. This is OK until about the 3rd week of flower where the plant hormones radically change the runoff as it focuses on bud development. I know I wouldn't risk it.
I hope this clarifies my position. If you don't see the logic in it, go for it.