3x is good since you don't have heat issues. make sure that your intake is at the furthest point away from the exhaust so that all the air moves. what do your roots look like? inspect the rootball of a dead or dieing plant for root disease/rot. maybe it could be some wierd type of virus or something
All the books I have say the same thing... clear the room in under 5 minutes...
The intakes and exhausts are on the opposite sides of the rooms. Intake in 2 feet off the floor in one corner, with the exhaust pulling through a carbon filter way up high in the opposite corner.
There is some negative pressure in the rooms, though. Not sure if this has anything to do with it.
I picked up a cheap CO2 test kit and will be checking CO2 ppm later as well.
The last time I checked any roots they looked really healthy... abundant, pure white, etc... but I'll check one of the clones that are having a hard time later today after the lights go on.
Virus? Can't rule that out. Does anyone know anything about plant viruses?