I thought these two photos might be of interest to those of you with embedded aluminum tubing thru-hulls. This is my sink drain. The aluminum seems to be in fine shape. http://www.bright.net/~htmills/Msinkdrainthruhull.jpg This is the upper end where it connects to the bottom of the molded-in fiberglass sink. The aluminum tube here was in awful shape. What you are seeing inside the rubber hose (which seems to be in excellent shape) is the remains of the end of the aluminum tube. What is left on the bottom of the sink is a very jagged and perforated tube. I'm surprised at the difference between the two, but I suppose it is because the upper tube is immersed with a much greater frequency than the lower (which probably spends its time mostly immersed) and thus probably lives in a sea of ions that are waiting to catch some cute aluminum ion. http://www.bright.net/~htmills/Msinkdrain.jpg Tod