I'm planning on growing in a small cabinet... Do you think it's enough to force air in at the bottom and then just have a vent at the top for the exhaust? or should I have a 2nd fan on the exhaust?
I'd go with the exhaust fan on top and create the vacuum. It gets rid of the warmest air, and the passive intakes will keep the cool air moving in the box. I'd also add a small oscillating fan to help with air movement and stem growth.
a good idea at the start when the plants are really small is to point the fan at a wall , if u have one close to ur plant, the air will LIGHTLY bounce back and just create a small draft against ur plant. Have the fan pointing at the wall on a angle , dont put the plant , then ur fan, then the wall .. angle it so that the fan is beside ur plant pointing at the wall and the air is bouncing off it and going towards ur plant.
a good idea at the start when the plants are really small is to point the fan at a wall , if u have one close to ur plant, the air will LIGHTLY bounce back and just create a small draft against ur plant. Have the fan pointing at the wall on a angle , dont put the plant , then ur fan, then the wall .. angle it so that the fan is beside ur plant pointing at the wall and the air is bouncing off it and going towards ur plant.
Socom is dead on. Always keep air moving around your plants. I can tell a huge difference in main stem thickness between my first plant which didn't have a fan on it til later and my younger plants which are constantly fanned..