Buderus Logalux LT200 - corrosion?

paulatrb

I bought a house that uses this water heater type. I decided to change the anode as there were no records and it is a 12 years old tank. I opened the tank and cleaned it. I noticed piting on the sides of the tank. The interesting thing is that the anode was in good condition.I was also properly grounded. Is this normal?. The tank is coated with blue ceramic. How do you get pit rust?.