Power Supply: Use a good 12V battery charger.
Anode: Recommend look around for a old table saw blade. They work well.
Caution; Be careful using a bathtub. Check to ensure it is a fiberglass tub, not metal. And be careful with the battery charger... put it on the floor, not on the same level as or on the edge of the tub. Of course Kids must be kept away. All of those issues is why I use a surplus 55 gal plastic drum with lid and keep it in the garage.