A link to a video of an inspection for a group of zinc sacrificial anodes is above. The video is very long but all of the anodes have the same buildup on the exterior surface. Could this buildup prevent the functionality of the sacrificial anode? The anodes appear to be in pristine condition and I wanted to ensure that this was not because of the buildup preventing passage of current.

I am a mechanical engineer, so I have very little knowledge on this subject.

  • 1
    $\begingroup$ Perhaps ask this on Chemistry. $\endgroup$
    – Solar Mike
    Mar 16, 2021 at 13:41
  • $\begingroup$ Look out, buddy, this is squarely in the ME wheelhouse, it's why you took materials & chemistry. $\endgroup$
    – Tiger Guy
    Mar 19, 2021 at 17:44

1 Answer 1


The anodes may develop fouling but they still work. Most often they are aluminum , possibly alloyed ( eg. Galvalum ). The protected steel builds up a "calcareous" protective surface layer with time and then need less amperage. Anodes may also be replaced if necessary. Strong current flow ( tides ), especially with silt may clean off the calcareous layer making protection more difficult ( more amperage) , so impressed current may be used. There are many books, classes, and companies devoted to cathodic protection . NACE would be a good source for references.


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