dr120 fan help

hi guys just need some info for a friend he wants to know if you guys leave your fans on 24hr? he has a dr120 with 600w hps 125 rvk intake and a 150 rvk out take with carbon filter just starting out so wasnt sure if the room would be too cool with constant fans obviously i know it would be trial and error but any suggestions would be appreciated barnzy

anyone? ok well will air still get in from the fan and duct if there not running? obviously not alot but will air still get in and would air still go out throught the filter and be filtered if the out take fan is not switched on? giving off smell would be a problem where it is any ideas anyone?

run it 24/7 so u have a negative pressure smell should not leak