After four years working properly, it is time to do the maintenance of DHW storage tank from the solar thermal collector changing the magnesium anode which prevents the deposition of oxide by galvanic protection .
Sacrificial anodes will last more or less depending on tank size and the degree of degradation thereof , that is; if you have many areas without paint, he's paid to oxidation and anode (magnesium in this case) will provide more ions, degrading its structure more quickly.
First of all, we acquired a couple of sacrificial anodes, are cheap, about 15 € each (I ordered them on Ebay for a company of Madrid). To change it, release the cover ( IMPORTANT empty it first ), loosen all the lime and use mud accumulated over the years:
