Originally Posted by beerocd
I've read magnesium is supposed to be the better anode. Plus there something weird about going all stainless and then dropping in a hunk of aluminum. I also read one guy used an aluminum nut to hold in his heating element so he just replaces that nut every so often and it keeps other parts from rusting.
yeah, magnesium's better. but practically speaking, these things are meant for hot water heaters where they have a much larger surface area to protect. my guess is that in this context, the difference in metal type doesn't matter. our HLT's and boil kettles also don't have liquid in them 24 hours a day for years on end.
unless a system is 100% stainless, you'll get rust. heater elements aren't stainless.
a side note, i believe i read that the protective anode has to be in direct contact with whatever you're trying to protect, so i just make sure the end of the anode is sitting on the element/locknut.