Was doing some experimenting with the aquatec pump but mostly to try out 3/16 drop lines 7' long. with the 7' i could hold a vac of 5-6.5" of vac. then i converted to 3/8 tube and tried that. pump when dry did 7" and i wanted to see if that added to my vertical vacuum. It did and a whole lot more. i get what you mean about keeping the membranes wet. i was able to pull 25" of vac on my test with the drop held high. i think i have a small leak on my riser as the first time i held 25" much longer.
Maple Flats- to use your bypass idea i could go 3/8 out of the pump, back to 3/16 into a 3/16 tee? then send the 3/16 bypass back into another tee on the 3/16 drop prior to increasing to 3/8 on pump inlet? any sort of valve needed there? would that not grab gasses too? I just want to do what i can to get it right the first time. Thanks in advance for the info!