I ran my tent before planting seeds, but discovered the temps and humidity are higher when there are plants in there. I have the back vent open in my tent because it was too hot when closed. The extraction/carbon filter seems strong enough to create negative pressure inside the tent, so I don't have any smell leaks, although that might change when in full flower. I have a small intake pocket fan sucking air in, but find it makes little difference if temps outside are warm. Initially, my temps were always 30-31F, but I bought a much better (and cheaper) carbon fan and it maintains temps bellow 27/28. During veg, I believe temps should be within 20-30oC (70-85F). Flower 18-26C (65-80F). Humidity during veg 40-70% and flower 40-50%. My plants are in early flower and before the new fan, humidity was sitting at around 60-65%, but I believe you can get by with this as long as there are plenty of fans blowing air around. With the new fan, humidity sits below 50%. Maybe some of the more experienced growers will have a different idea