I went to the local hardware store and picked up a inline fan which does 500 cfm. I have a small duct which runs from my window to a exhaust tube which runs to the top of the grow room. I hope that the exchange of the air will help with the yellowing. I will keep everyone posted in the next couple days with pics and such to see if they perk back up and start to shoot again. Thank you for the help Baldy!!!