In a 4x6x8 room I used a whole house dehumidifier just to keep it under 40%. Ventilation during light cycle. It could barely keep it down. The rewards were way better than moldy buds or small buds from RH too high. I live where RH is always high.70 to 80% normal. Out side growing sucks here and so does weed grown out side. AC essential. Like said go cheap grow cheap. 3 hit crippler, couch lock,trip your ass for 3 to 4 hours. It's worth it.