400 HPS FTW!

my closet is 22.5" x 22.5" x 67.5", and I have a 400w HPS with cooltube and 129 cfm inline fan pulling air through a carbon filter first, then the cooltube, then the fan which is outside of my closet. Temps are a little high but within range, so for your dimensions I'd get a stronger fan than mine... Second link in my sig has more info. Good luck!