magnesium or aluminum, that is the question ? ?

Suburban WH are the only ones that use an anode rod. Aftermarket sells anode rods for Atwood but they are not needed...Atwood doesn't supply them OEM.

Suburban is a steel tank that is glass-lined..hence the need for anode sacrificial rod...protect the steel tank (Atwood tank is Aluminum Alloy)

Aluminum rod lasts longer especially when water quality is good.
Aluminum can 'grow' deposits..calcium will collect on rod....just wire brush off.
Magnesium will deteriorate quicker than aluminum BUT can cause a sulfur smell due to reaction to microbes in water source.

As long as anode rod is deteriorating it is protecting the tank.
Faster deterioration doesn't mean it's working better...just deteriorating faster.

No need to change out until 75% of rod has deteriorated

ChopperBill wrote:
Had an aluminum rod. Worthless, did nothing. Put in a mag rod and a year later it was done.

I'm finding that out myself. Doing my annual WH maintenance, and the rod is corroded, but not much. Lotta white chunks coming out.

For years I've used Al, as shown in the manual. I just called Suburban, and she said that part has been changed to be Mg.

So Mg it is!

Had an aluminum rod. Worthless, did nothing. Put in a mag rod and a year later it was done. Place we stay in winter the water is krap sure the mag did it's job.

If you have an aluminum hot water tank, then an aluminum anode will do NOTHING to protect your tank. IN MOST cases however aluminum tanks are fitted with plastic (nylon) drain plugs so no anode rod is required.

Assuming you're referring to the sacrificial anode in your hot water tank, the reason the aluminum rod comes out relatively clean is because it's made of the same material as the water tank. Thus you have no sacrificial anode to speak of, and any debris you manage to flush out of the tank consists of particles from both the tank body & your aluminum rod.

On the chemical scale of activity i.e.,electronegativity, magnesium is more electronegative or active than aluminum, hence the reason it is used as the sacrificial anode in the water tank. This means that the magnesium anode will dissolve or corrode first, sacrificing itself instead of the walls of the aluminum tank. When you replace the magnesium rod with an aluminum one, you removed this sacrificial rod.

Depends on your h/w heater. You want the rod to be lower on the galvanic scale than the lining of your hw heater so it deteriorates first, hence "sacrificial" anode.

Some (many?) are ceramic lined, so either will do.

If you have a very bad smell to your hot water, use aluminum, otherwise the magnesium will do just fine.

At $10 every 5 years or so, it's not that expensive either- unless you're full timers who use it all the time.

Gernerally speaking, use magnesium unless you have problems as mentioned, then switch to aluminum. Same advice for home water heaters (I've switched a few to aluminum due to poor water, mostly well water, to eliminate the smells)

I also use the Al rod. Its made for worse water conditions and therefore lasts longer.