Magnesium versus aluminum anode rods

I couldn't get a replacement magnesium anode rod for our 6 gallon Suburban water heater, and put in an aluminum one. However, we notice that there's a terrible sulfur smell that comes back several weeks after the tank has been thoroughly cleaned with vinegar. When we used magnesium, we didn't experience the sulfur smell, and am wondering if others have had that experience. I'm a bit confused, because some folks say that there's the sulfur smell when using a magnesium rod. When we look at the aluminum rod, its diameter has hardly changed, but there's always white crud on it. I recall that the magnesium rod deteriorated a lot faster, but isn't that a good thing?

Thanks in advance for any help.