I agree a five inch will be fine. I have a tent of similiar size, with 550w hps cooltube and use a 4" 200cfm on a var. control for exhaust and another 4" for intake. I use my homes crawlspace for intake air....with cold weather and available intake air being cold, I can keep both fans on very low speed and maintain 70-80f .....
I would do a 6" for the simple fact of that (for me) I always see 6" ducting and accessories and such but haven't seen much in the way of 5". That may or may not be an issue for you. I also tend to be a go big or go home type of person.
I would do a 6" for the simple fact of that (for me) I always see 6" ducting and accessories and such but haven't seen much in the way of 5". That may or may not be an issue for you. I also tend to be a go big or go home type of person.
True, I have seen that 4" and 6" ducting and accessories are more readily available at hardware stores than 5".