soil/ coco mix ph test question

Hey guys. This is not my first grow but i am growing in soil for the first time and i have a question about ph testing the runoff. I recently noticed some slight yellowing and necrotic blotches (also what i believe is rose setting) on my girls and the reasearch i have done is leading me to believe it is a ph lockout problem. I am growing in soil/coco mix about 50 50. To do the runoff test i phed the water to 7.0 then ran it through one of the buckets untill runoff and ph tested the last 5% of the runoff. The ph was at 6.5. The guy at advanced said that i should be aiming for 6.0 with a soil coco mix (for the ferts and water). Any help appreciated i am just trying to figure this soil thing out.

it sounds to me like you are in the clear. i like to keep my runoff at 6.3. are you in veg or flower and what week. a little yellowing is usually a N problem but if your run of is 6.5 than its not locked out. it is probably not recieving enough N.

i am in the first week of flower. I first noticed it after watering with bud blood. I figured that i was low on n as well so i gave them 500 ppm of grow nutes along with a bit of cal mag (2-0-0) and now i am noticing a bit of burn on a couple of them. None of the problems are really horrifying but i just want to eliminate them early. Thanks for the help