[rohrmann]

This is from the Suburban manual-

NOTE: Water with high levels of iron and/or sulfate will increase the rate of deterioration; therefore, more frequent replacement may be required. If anode rod is mostly eaten away, replace it with a new one.

The Suburban magnesium rod is part number 232767
The Suburban aluminum rod is part number 232768



If you replaced the original rod with an aluminum rod, like was said, it won't sacrifice itself to protect the steel tank. An anode rod replacement every 12 months is way cheaper than risking having to replace the water heater due to a leak caused by corrosion. I use only the magnesium rod, and some years the rod is mostly gone and others it is maybe half gone. Just depends on what water runs through the water heater.