A carbon filter is optional. An intake fan will be needed at some point for air exchange. CO2 is needed for plant growth and so once the plants use up the CO2 in the grow space, the plants growth will slow down. An intake fan will exhaust depleted air out and bring fresh CO2 in.
Awesome thank you. what stage will that be needed by ? At the start of veg ? Or ASAP ?
@brandonolson199923 Many growers will keep the carbon filter off until the flip to flower since the plants mostly smell when they have trichomes on them. As for the the inline fan, you can get away with less air exchange when the plants are seedling and even early Veg, although, you could see slower growth if there's a lack of CO2. Therefore, it's generally recommended to have an inline fan for proper air exchange throughout the plant's life.