Yeah runoff means simply nothing unless you have aproblem.if things go well,you are fine.dont get yourself confused with runoff,especially if they are seedlings.as time passes,youll notice your runoff ph drops because of all nutes you are giving to them.plagron rocks btw.
If you would like to hearmy opinion,I use plagron coco and nutes too and my ph is 6.1 in veg and 5.9 in flower.somewhere around these numbers.i dont know i find 6.1 better for vegetative growth,my plants love it. Feed frequently and plagronwill pay off