fresh water system

I have a 2002 Hunter 260. Last season was my first sailing season of ownership. Unfortunately, I discovered a nasty water tank (black stuff coming out of the both the galley pump and head pump. During the winter, I had a deck port installed in the top of the tank to facilitate clean out...

Has anyone experience with replacing the fresh water vent hose on a 1990 Hunter 35.5? My problem started when I found it very difficult to fill our fresh water tank. My first inclination was that the vent line was blocked. I was able to fill the tank after removing the vent hose from the tank...