You need a friend to step in to help you? It looks like he barely has any perlite in his pots, so there could be shitty drainage going on causing root rot. I'm not saying you do 6.5-7.0 in 95% coco media. I'm saying that there are issues with having soil in coco and ph'ing to 5.8. The soil could cause damage, so could proper drainage, so could overfeeding, so could only having your ph @ 5.8 the entire time in coco. Yes, the soils amendments could be gone NOW, but maybe not when the problems started.