Hi!

I'm growing El Nino. One week ago, the leafs of one plant started to geting yellow, and now its dry. And now the other plants have the same problem. I started to use ph corrector 4 days ago, and now they are much worth than in the begining (pH 6/pH6,5).
But I have Ultra Haze and Nexus type of plants also in the same area and they are healthy. Please help me. (I'm thinking about it could be watering problem or maybe some insect, or PH?)

Thx