hello Caroline
Yer u wanna have a fan blowing on them 24/7 - helps to circulate the air and really builds the stems up.( which u need to take the weight of the buds)
Are u planning to flower them all using just 2X 200 watt envirolights cos i don`t really think those lights alone will do the job to be honest.i`d say u`d need at least another 3 or 4 of them lights in there or a 400W HPS to really grow some fat buds.
How old are they by the way??Have u checked any of them for sex yet? i`ve got a plant at the mo that was showing sex at only 4 weeks into veg so u need to keep an eye out for males and get rid of them as soon as u spot them.
Hope this helps in some way
Digi