Without the fan it's just passive airflow, no forced, I will be on my thrird grow in hoop this summer as well, I used two 30 inch industrial fans from nards. One sucks in, the other blows it around an I have two of them cheap induct 6inch fans that I use for exhaust. The inline fans are on a plug in thermostat. When it hits 75 F they kick on. I'm no expert or even novice in the hoophouse. Like u I'm on a try an fail basis. All I know is if I don't have massive air movement I ran into problems. I'm looking forward to this years run, 50 gallon
smart pots an roots sent me enough free shit to actualy run a full on run. Stoked for this year an like u I have some of the same beans. A lil inside info....... Get the gth crosses while u can. THEY WILL NOT DISSAPOINT!!