is there a specific stage of growing that ventilation should begin running, or do I just turn it on at seedling and let it constantly go, adjusting for climate parameters?
I am running a 6inch filter and fan in a 4x2 tent.
When the plants are seedlings, they won't intake as much CO2 as they will when they are bigger with more foliage. You can get away with a small fan to circulate the air and change the air in the space 1-2 times a day. But when the plants grow up, changing the air more frequently is a must or else you'll encounter slow growth. Many growers just leave their fan on 24/7 as long as their temperature and humidity are good.
When the plants are seedlings, they won't intake as much CO2 as they will when they are bigger with more foliage. You can get away with a small fan to circulate the air and change the air in the space 1-2 times a day. But when the plants grow up, changing the air more frequently is a must or else you'll encounter slow growth. Many growers just leave their fan on 24/7 as long as their temperature and humidity are good.