Phat Filters HEPA Filter Intake KitPhat Filters Intake Kits Are A Great Solution For Ensuring Contaminants Of Any Kind Stay Out Of Your Grow Environment. The intake fan and filter of your ventilation system have a very important job. They are responsible for bringing in the fresh air, while the exhaust fan and filter remove the hot, smelly air from the environment. It is important to use a filter with your inline fan because you only want clean air coming into your growing space. HEPA