Hey all on my second grow. On my first and this grow after around 10 -14 days this has happened on Both occasions. Ive tried doing research and found possibly root rot or calcium deficiency is the problem based on photos I've seen. Im running canna a&b , cannazym and rhizotonic all at half dose, calmag at 1ml per 10l as suggested ph 5.5 in coco with 600w led 25c temp with a good airflow and carb bag inside. Seedlings are not leggy at all and up until today (day 10) they were looking great. Within the last 6 hours this has appeared on the leaves and now I'm worried about loosing the plants or stunting beyond salvage. Any ideas from past experience appreciated they were germinated on 2nd june and planted on 4th and have been flying since then until today.