Why are fans necessary?

Helps circulate air, cools the area, and helps strengthen your plant.

 

you need fans.


/End of pondering

 

Also helps the leaves breathe. I had too weak a fan on my plant and where the leaves were laying on each other would be wet. This could kill the leaves and lead to mold.

 

would you want to live your life in a room with no circulation/fresh air?

 

A fan blowing on the actual plant will strengthen stems, but you need an exhaust to properly cycle the air.

You can have passive intakes but you need an exhaust.

 

Plants need CO2 to survive. As leaves absorb CO2 from the air to use as food, they can only collect from the air that is directly around the plant. If you don't have air circulation, you can have a room full of co2 rich air, but the air directly around the leaves will be sucked dry. You need to have air movement so that the plant is exposed to new, co2 rich air constantly. Not having a fan can cost you ounces of bud by starving your plant of food.

The exhaust fan is a whole different story. The point of the exhaust fan is to control the temperature inside your box. Too hot and you'll cook your plants. Those grow lights put off a ton of heat. If you do it right, you can make one fan control the temp. and circulate the air. But I find that you need at least two. So you can circulate air when the exhaust isn't needed.

 

The carbon scrubber is nice because it absorbs all the smell from your room. Otherwise your exhaust will smell like a cypress hill concert. You need an intake... but you don't always have to make one, If your grow room isn't sealed shut. If it's not an air tight room, you can get away with just an exhaust. But if your room is air tight you will have to have an intake. I think that having an intake is best, no matter what. That way you can control where the air entering your grow room is coming from.

 

Yes you need intake and exhaust. You can't exhaust out of a closed space, that would create a vacuum (if your fan were strong enough). Ventilation means moving air in and out, not just blowing the same air around.

Yes a passive intake is just a hole.

You need ventilation for up to three reasons:

- First, the plants need fresh air. They need CO2 just like we need O2.

- Second, heat control -- if you don't vent the heat from the lights out and replace it with fresh cooler air then the grow could get too hot for the plants

- Third, odor control.

 

Well what kind of scrubber do you have? If you have an exhaust system set up, it will most likely run through heating duct work. They make carbon Filters that attach directly to the end of the duct work. If you are making a home made exhaust system, then the carbon filter will have to be attached in a home made fashion also.

 

Whatever kind of fan you can mount in a sealed airstream -- you channel in all the air that the fan moves and then channel all that air out where you want it, no leaks. That can be a can fan, squirrel cage fan, any type that you can seal the airflow. And better to get too much fan than too little.