is this worth it on a 13 yr old water heater? I am unsure what maintenance has been done to it

Hi! Yes, using a Corro-Protec anode rod on a 13-year-old water heater can be a worthwhile investment if the water heater is in good condition, with no visible signs of leaks. Installing a Corro-Protec rod can help extend the lifespan of your unit by protecting it from further corrosion. Additionally, if you are experiencing sulfur odors (commonly described as a "rotten egg" smell) in your hot water, the Corro-Protec rod is highly effective at eliminating this issue by reducing the bacterial activity responsible for the odor. It also helps minimize limescale buildup, enhancing efficiency and potentially delaying the need for a replacement. Thanks!