I've been growing heli's for a few weeks/months and suddenly noticed that 3 or 4 of them have developed black spots at the tip while developing. One of my Heli's went all black this week, and now another is starting to go black as well. What am I doing wrong?!
30,000K lumens T5's about 8" away from the tops of the plants.
Temps between 60 and 75 degrees night to day.
Humidity between 75-100%.
Constant airflow during the day.
Moist but not sitting in water media.
Media is a mix of orchid bark, LFS, and APS
Here are pictures.