like i said in my first post......run off is bullshit, if you think its a pH problem fucking run 5 gallons of 6.5 water threw your medium, that WILL fix the problem as long as you correct your pH b4 you water or feed from then on, if its simply a lack of nutriens and gets lworse, obviously you need to bump your shit up... but i should mention iv grown plants without pHing my water in FFOF, fuckin water goin in a almost 8 with healthy green growrth, the buffers work in the soil...now you might have a slight salt build up, in which case the 5 gallon "flush" i suggested will still work...
EDIt, like benny said stop foliaring too