Fairly new at this and feminized plants are trying to die. 7 wks and largest is 7" tall in solo cups, holes in bottom and around outside edge for drainage and air. Yellow leaves on bottom started after being in solo cups about 10 days, used CoCo Coir for medium. Bottom leaves started getting yellowish and then got brown spots on them. Not around edges, more in center of leaves. Yellow/gold leaves spreading up plant. Tops look healthy but growing slow I believe, very light green in color. Have them on a heated pad on my bathroom counter to help with humidity as I live fairly northern in US. Initially seedlings loved heated pad kept at 75 degrees. In last 5 days turned pad off as it seemed to be at 80-81 most of the time. Weather here is getting warmer, have windows open. Put plants in window sill of open window during daytime, last 3 out of 5 days, then back under grow lights to finish light hours, doesn't seem to change anything. Stems seem to be strong for the size of the plants. Tried nutrients, seemed to make condition worse. Tried bottled water with minerals, seemed no change, if not worse. Tried plain well water, no change. Have blue spectrum grow lights over, tried 18/6 hours seemed to get worse, put back to 16/8. Humidity now is 55-63%. Last year plants grew pretty well, just a little smaller than would have liked. Does anybody have any idea what I can do to try to save my plants??