Calcium/lime crusty stuff. I have a drainage valve but even when it is full open it only dribbles.
How old is said water heater?
Vinegar works if the crust is not too thick. I will, from time to time, remove my shower heads and soak them in straight vinegar. I also have to scrape gunk off the base of m electric toothbrush weekly. Here the water is hard.
Relatively new.
I found my answer on about.com
http://www.chilipepperapp.com/flush.htm
Hello AVers
Glad you found your answer. Hi Nano!