Strange Water Heater Anode look.

[MarekP]

Only by an accident I've learned about anode existing in water heaters. Since my heater sits (and still works) somewhat about twenty (20) years (despite nine (9) years warranty), I've decided to change the Anode. I found all necessary info on the internet.
However, my old Anode has quite different look, unlike any described in available sources: the water never smelled bad or had any discoloration, but the Anode has a DARK BROWN build-up all over its entire length, and under this layer of buid-up, there remains INTACT Anode , unlike those shown in available sources. The year of production of the tank is 1996, yes, it is 20 years already and all time is ON, never was shut-off.
I have a question: what is wrong with my Anode / heater / water? Why this strange build-up, instead regular weared Anode?

 

[SHR]

Nothing is wrong. You are blessed with good water that has not eaten away the metal of your water heater. Rejoice!

 

[voletl]

To each their own but if I had a water heater that lasted 20 years I wouldn't touch a single thing in it or on it let it do its thing but hey that's me

 

[KULTULZ]

...my old Anode has quite different look, unlike any described in available sources: the water never smelled bad or had any discoloration, but the Anode has a DARK BROWN build-up all over its entire length, and under this layer of buid-up, there remains INTACT Anode , unlike those shown in available sources.

The anode is most likely passivated.

The brown buildup, is it a solid or slimy? Iron bacteria most likely. Well water?

 

[MarekP]

The anode is most likely passivated.

The brown buildup, is it a solid or slimy? Iron bacteria most likely. Well water?

Thanks everybody for response.
The buildup is solid and crusty, very easily crumbles, about 1/8" thick, very evenly clad along the rod, so my first impression was that it is the rod itself with a thin layer of some discoloration. Water is from the grid (Chicago, IL), not from a well. Color is rather somewhat between brown and black.

 

[KULTULZ]

The buildup is solid and crusty, very easily crumbles, about 1/8" thick, very evenly clad along the rod, so my first impression was that it is the rod itself with a thin layer of some discoloration.

Water is from the grid (Chicago, IL), not from a well. Color is rather somewhat between brown and black.

It may be coated with calcium carbonate which is usually white in color. Yours being brown and dry may be from magnesium and or iron discoloration.

You can usually wipe or wire brush this off.

Water heaters can fail from any number of impurities but you seem to be blessed. Your water pH must be spot on.

 

[MarekP]

I've re-examined the rod, and I found: the impurities come in layers: first layer, the one closest to the rod surface is light grey, pretty hard and unevenly clad. Next layer is thin and brown in color. Finally, on top of those comes black, solid but crumbling easily. The rod itself shows some decrease in its thickness however; it is pretty smooth however, with some bumps on its surface.
The heater is GE made, self-cleaning, natural gas. See attachments.
I consider this forum very useful, thanks to very kind members.