How long can the system be open before the dryer needs to be changed? A day, a month? Thanks as always! Charles McCall 1985 DeTomaso Pantera GT5-S #9375 "Raising Pantera Awareness Across Europe" <http://www.poca.com/index.php/gallery/?g2_itemId=2323> http://www.poca.com/index.php/gallery/?g2_itemId=2323