Ventilating your grow area is key to a healthy crop and a beginners guide can be found here. It removes excess odours, heat and humidity, can prevent pests and diseases and can control co2.
Fans can come in all shapes and sizes depending on your needs. RVK’s are popular as are quieter box fans and inline fans. An EC fan can give precise control and lower running costs than older AC fans but are more expensive to buy.
Filters are carbon filled and can remove odours from your area when connected to your fans using ducting. They are generally placed in your grow area with fans pulling air through them and out.