I used a hunk of clear vinyl tubing to replace the foam aspirator hose. Your plastic tubing will work fine. You may want to take a look at the evaporator drain hose, as it's made out of the same foam material. When that one goes, it will fill the rear seat footwells with water.
2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg
And remember folks, Only You Can Prevent Hilliary.