Seeing brown spots on the leaves. Assuming it's a calcium deficiency. Added another ml/gal of Cal-Mag for the daily feeding. Besides that, what else could it be? Also, at what point do you water plants in coco twice a day?
That looks like some older growth. New growth will show you if a problem has been corrected. Old damaged leaves won't fix. As long as it's not spreading and it's only one that one or two older leaves I'd just keep going. 🤘😤