Nope, that white stuff is salt build up from nutrients. I've tried to get it off but it's like concrete. It's because of the fabric pots. I read that they were great for dripper systems but there was no mention of anything like this. So I learnt something and that is that fabric pots in hydro collect salts. This brings me to your next question. That is excess nutrients right there. Unlike the Fruit Tree that wanted more this one apeared to want less. The nutrient build up may have also contributed to this. It's that shared res againIs the white powdery looking stuff diatomaceous earth? Also, those crunchy browning leaves...is that fade or excess/deficiency?