Hey again! You're probably sick of seeing me post so many questions, but I'm trying to make my second growbox, and I wanna make it right. I've been most confused with airflow since I started growing.. I recently bought a normal bathroom exhaust fan from the hardware shop. Little did I know 1.08 m3/minute only converts to 38.17 CFM.. but I'm confused because the fan blows pretty hard. But why is the CFM so low? Most PC fans have a CFM rating higher than that even and are more quiet. QUESTIONS: 1. How do you calculate the total CFM of your fans? Lets say the minimum is 150 CFM. How will I know that my fans are enough? Do I add the CFM's of all fans? (including supplementary fans inside?) 2. MY BOX DIMENSIONS are below. This is where I get really confused... So I use a calculator and give my dimensions. Results came as 3 for minimum CFM. That shocked me cause it felt too low.. THEN, I changed NUMBER OF LIGHTS from 0 to 3, then outta nowhere, Airflow Requirements jump to an outstanding 453. WHY is it so high??? Now it shocked me cause it was too high. WHAT is my true requirement? I'm doing an LED and CFL mixed grow. 1 LED panel, 2 CFL bulbs. Tomorrow I'm getting 2x 120mm PC fans that are 77 CFM each. does that mean I have 154 CFM??? If you guys need more images please let me know. And forgive me for my assertive tone, I've just been confused for the longest time and now it's frustrating me because I can't continue finishing my growbox until i know what I need... Thank you so so much