The leaves get yellow after a few spots show up. They're green when the first ones show. Spots get bigger and leaves yellow.
Humidity varies between 30 - 38%
Lots of air movement.
Grow area is 4' x 12', which is within a 14' x 18' room.
Grow area is exhausted with 6" duct and fan, into the 14 x 18 room.
I enter the room many times a day.
The grow area has a 14" x 22" filter for passive intake.
pH is low in growing medium, around 6
pH of water is about 7