Back2grow | problem in early stage

So i started my new grow one month a go, growing Blue mystic
in Coco+per in a 8 liter pot, 250w Dualspectrum bulb. feeding with Sensi Grow A+B.



i started to feed her 3 weeks ago, starting with 0.98 E.C, now im on 1.3 E.C.
runoff seems to be fine (1.4 the last time i checked) PH is 5.5-6 every water.
i started to see these signs lately and i don`t understand whats going on.
I read the "diagnose" page and it looks like Root rot :
http://www.growweedeasy.com/root-rot

idk how it can happened with coco cuz from my experience its really hard
to over water plant in Coco. Still my thoughts are that i might feeding too much,
im watering every 2 days max. (by the way i`m going to switch to flowering soon).

ill be glad to hear your thoughts =]
thanks all.

Just opinion, coco has a way of not gettng enough calcium to the roots. Maybe some extra cal-mag could help. Since she isn't curling, you could probably get away with that. If it is root-rot, I would use hydrozyme. I used to use h2o2, but that hurts my other beneficials in the medium. It does work for root-rot though. How much light do you have on her and how close? Are you supplementing co2? Is the air being cycled enough? Do you foliar spray with the lights on? Could this be a temperature problem? What are you running with lights on, and what is the temp in the dark? Just trying to see the situation from as many angles as possible.