i've been growing in coco a while, and i've seen your questions/problems before. optimal ph for coco is 5.8. (next time you use coco/transplant, add 15-20% perlite, really beneficial.) about your crispy leaves, once they get that way, they wont be back, so just yank them. i think you were talking about the ph of the run-off, and the coco itself. i also think i read someone talking about ph'ing your feed to get the mediums ph back into range. what else, flushing, i can't remember the rest, and i don't want to be bouncing back and forth, lol. the only thing that you should be concerned with regarding run-off, is that you get enough, (10-15% is good.) chasing ph, trying to get the run-off ph, to match the ph of what you feed, is a waste of time. as long as you properly ph "everything," you put in/on the plants, ph should never be an issue. as the plants drink/eat, of course, the mediums ph is gonna fluctuate. this also means that the run-off, (of course) will also fluctuate. only makes sense, right??? now just because the medium/run-off ph is different, doesn't mean automatically, that your plants are gonna display issues. it's pretty much the same in soil. i feed every day, and allow for run-off. this run-off acts as a "mini-flush," and keeps things from building up, which is a good thing. so as this build-up washes out, the ph is gonna be different because there will be added nutes... so the ph will constantly be changing because of the addition of nutes, and or the removal of water the plants drink. you don't wanna flush coco, cause your run-off does that, and at the same time, replaces old/depleted nutes, with fresh ones. hope this makes sense, i'm a little high, lol...