Which anode rod to replace

[peppster66]

Hi guys, just pulled the old anode rod out of the water heater, starting to deteriorate, just want to replace it, but there is aluminum or magnesium, just wanted to ask if there is a preference on these, or one that lasts longer, lthanks for your input,,,,,,take care,,,,

[GeorgeRa]

This is the key information to answer your question - Galvanic Series (electrochemical series)

For steel tank all anode rods are OK – Al, AL/Zn or Mg but for aluminum tanks Mg would be necessary except I am not aware they use anode rods. So, check your tank, I think Atwood is using Al tanks.

Make sure there is a direct electrical connection between the tank and the anode rod’s thread, the electrical potential based on dissimilar metals (tank/anode) is necessary for the anode to protect the tank, otherwise it is an electrically floating piece of metal in the tank, useless, so don’t use too much teflon tape.

[rowiebowie]

Go with the magnesium. Only a few $'s more and it gives more protection than aluminum as per the chart provided by GeorgeRa.