Hello I've gotta problem with my plants. They are growing very slow and have brown spots and yellow leafs. I have Coco water pH between 5.5 and 6 adding calmag when watering but they are really poor looking.
coco causes this issue if it was untreated to fit the needs of a young plant. plus tapwater is not the best choice to use too... try to flush that medium with rainwater or r.o water with 0.3 mS ec and get an ec meter
yes, some "bio" coco and mixes can be infected.... they should disinfect it or pasteurise it, but if they would do that it would kill the beneficial stuffs too.. it can be a trap