Sulfur smell

Had that problem in a Jayco park model a couple years ago. Drained the HW heater and refilled it with a cup of bleach added. Let it set for a few hours. Repeated it. End of problem. Was a brand new heater from Lowes(20 gal) The owners manual said it was a chemical reaction with the anode, and there were 2 types of anodes(magnesium & don't remember what the second one was) If I replaced what came with it with the other type it would eliminate the problem-but no one knew what kind was shipped with the heater. Hence the bleach. Gary