I'm still in the process of designing my first system and have started to wonder about the size of my outlet tubing.  I plan to fill my beds from 1/2" pvc, but am not sure if I should make my drain outlets 3/4" or 1" pvc.   The bigger the tube, the faster it should drain.  But are there any negatives to using a larger diameter?  I'm going to make an auto-siphon out of a loop of flexible pvc....co…