Another benefit of cast iron tubs is that they are going to require minimal maintenance. For general cleaning, all you'll need is mild soap and a cloth. For more stubborn stains, a solution of baking soda, ammonia, and water can keep that enamel looking great. Over time, you may find that chips develop in enamel if heavy items get dropped onto it. Thankfully, enamel can be replaced and repaired to avoid needing to completely replace your tub. The enamel used on cast iron tubs is very resilient, so it's unlikely this will ever actually be an issue.