Is it the same strain you ran in the past or is it a strain your not familiar with.. The reason I ask is because some breeds don't like lots of nutes. I've never ran coco so I can't speak on it to much but I've ran across some nutrient sensitive plantsHaha no that is just coco. While putting it in pure coco might not be the best idea, I have been doing it for a while now and have not run into this problem yet so I don't think it is the underlying cause. Light burn is unlikely as well because it was 12 inches below the bulb. I follow this water cycle.
Nutrient water
nothing
regular water
nothing
nutrient water
nothing
regular water
nothing
so on and so forth. I am using flora nova in that cycle. Maybe it is not enough? It is hard for me to pin down because I have not had any problems like this and I have not changed any variables lately. Any other ideas? Thanks for the help guys!