my whole system runs off 1/4" jg tubing, it was enough to feed 8 of the biocontrols nozzles, however if doing it again, I would probably use the next size up 3/8 tubing and gauge down near the solenoids for better flow. I don't remember exactly how I plumbed the transition, but I did document it somewhere around october of last year in the thread for some others. It was a pita until I got the correct transitional pieces...