When using RO, liquid nutes, and supplements the PH has to be adjusted even using RO water. The problems with my OG Kush experiment were created by me...Soon to be remedied! The outdoor girls get plain ole tap water all the time after transplant to outdoors. I am not having to do much out there, worm castings, bat guano, fish bone meal make up their weekly (poop soup)
Yes, I realize this (since the RO water should be PH 7 and you want your soil PH closer to 6.5), but being a "hydro guy" I'm just not following how you get an accurate soil PH reading that way.
I guess that's why I'm a hydro guy!