Genuity, what are your temps and humidity in that dungeon without any hid lighting running? I'm sure it will all change once you have it up and going. I can't say enough what a luxury it is to have a room to grow in where you aren't confined.
I'm open to suggestions as far as the dry ice issue and micron size but it just seems to me 220 lets too much leaf material through. I also have a 160 and a 120 micron bag.
I ran the 160 bag the first time i ever did it, the kief was perfect, very little green in it. The problem was the bag got clogged after a few oz of trim was done.
I finished with the 220 bag, and didnt notice a major difference from the first run with the 160 bag.
Since you grow mostly sativa dom strains, I would think the 160 bag would be perfect for you.
I also noticed that the smaller micron bags are not built to hold up to the abuse from the dry ice. They freeze and get brittle, and can possibly break.