If you doing the negative pressure thingie and you want to stop the tent walls from being sucking in, make you some tent bows. A guy at one of the local nurseries makes them for all his friends. They're just a piece of bar-stock aluminum that is bent slightly outward like "Bow", and on the ends it looks like its 5/8 rubber hose cut in half, and the bar-stock is epoxied to the hose with some of that fuzzy automotive tape, (the cheap mans carbon fiber tape). And each end presses up against the tents frame so you can easily raise or lower them out of the way when you need to work in there, you use 2 on each wall, and it completely stops the tent walls from blocking light to those buds that always seem to get squished from the tents walls getting sucked in! And if you don't want to go to those extremes, you can always use curtain rods, but they don't work as well as using a slightly bow out 1 inch bar-stock aluminum does!