Well, I'm a little curious now as I know about internal bypass, but only when used to keep the maximum pressure from going higher than the setting as opposed to a demand pump that would have a pressure switch that turns the pump off until it senses low pressure again. Anyway, besides having an accumulator, I also have a solenoid within 2 inches of each nozzle, so there is no time really involved in pressurizing the line, and no mist run on after a cycle. The problem when those things aren't controlled is the larger mist particles splatter and over wet things at the inbetween lower pressures, not to mention creating a lot more waste when doing DTW. So are you saying that with your pump, there is instant 125 psi pressure available to the nozzles, but it also instantly dumps with the zip drip and there is no run on? I'd assume there is still some time involved in pressurizing the lines to the nozzles, and you couldn't run the short mist times that my system can. (It seems I can get a full mist to develop and cut off within 3/10 of a second)... The reason it's been found that the ability to have shorter mist timings is that the roots perform better with a less defined wet/dry period- so instead of misting for 5 seconds every 5 minutes, you are misting for 1 second per minute, or half a second every 30 seconds. With the correct droplet size allowing constant mist in the environment to circulate, the roots can simultaneously feed and respire resulting in faster growth rates.
I don't know exactly how they do commercial lettuce, I figure not often aeroponically, but more the style where it floats on the surface of the nutes in styrofoam floats. I was only saying that a homebrew diyer could probably perfect his system for growing with perfect attention to each plant easier and would be more likely that a huge operation that may have to sacrafice quality for quantity or budget concerns. IE just because they are using a method comercially, doesn't automatically make it the way for the end all be all of perfect results. I'm sure they have a vested interest in efficiency however. It's true that the arguement that a large corporation with deep pockets and resources "could" and probably does use good methods and won't waste time on things unproven by science, but let's face it- they are in a business of making money, where we might strictly operate on the passion of having the most perfect plants and roots we can possibly grow for our small gardens.
EDIT: Also with an accumulator I feel there's a safety net of stored energy so if the pump failes or there is a power outage, alot of the concerns people have about aero being so easy to foul are dealt with. Now I realize you still have to notice the pump's gone bad, and that there are other ways to have backup systems, but by the time you do any of them, it seems the best way to do things cost and efficiencywise was just run an accumulator in the first place if you are interested in having the best results as a main priority. I have seen rootpics both with and without an accumulator, and I know what I like. Have you been able to get roots like the ones tree farmer posts for instance, with your setup?
