I run my fans 24/7
the exhaust fan runs when the temp rises about 85 in the room, unless i'm useing CO2
then its off.
I'm going to use an AC unit this summer on the recycle mode to keep the CO2 in the room
peace
heart
heartsurgerysurviver Reviewed by heartsurgerysurviver on . FANS some people use the fan 24 hrs on their plants*****some use no fan at all*****some put it on for the light cycle*****some use it only for the sleep cycle.*****hmmm*****please say when anyones fan(s) should be on or off that is best for growing untill harvest. Rating: 5