If it’s glass-lined steel tank, which most of them are, then there will be one or more anodes. Look for a hex nut somewhere on top. If the tank is 10 years old and you’ve been softening all that time, it may be a new tank rather than a new anode that you’re going to need. They don’t last forever without maintenance. Time to read the Basics section on my website, especially the Anodes section.