Good point.

New HW heaters, too. The better HW heaters have one or two magnesium alloy anodes. Average and cheap HW heaters have a single aluminum anode. The magnesium ones work much better and will be pretty used up in an old HW heater. Lawnboy mower decks are a magnesium alloy, but have never filed / burned one so don't know if there is enough magnesium to make it worthwhile. Pure magnesium is soft as heck and burns far better than the alloys.

HTH,

Tom