How many times should my exhuast fan come?

It's a 2x4x7 tent with passive intake and 4" can fan exhuast. I have the fan wired an plugged into a Hydro timer. Seems this timer only goes in 15 minute incurments. I have it on the the timer to go on for 15 minutes and then off for 35 and then back on.

Question: Am I ok with the exhaust on this time or 15 minutes on/off for 24/7. Temps have been pretty steady between 72-76 w/42-60% humitdy. Plants are 2 1/2 weeks old. Thanks for the advice, it's greatly appreciated.

If your temps are good and constant then it's prb fine. remember Growing weed is not universal what works for one may not work for another.

24/7 is easier on your fan. It will not like turning on and off every half hour for months. It's highest efficiency is at max power; so just keep it always on.