In Florida as well as many states such as California it does not matter if you have city or well water. The water is hard. If you do not have a softener it can make things like bath salt soaks almost double in price because you have to use twice as much as the instructions say to get the desired results. That can get very expensive very quick.
I have found a cheap easy to make recipe for hard water that works really well.
One measuring cup
One large mason jar
Mixer or a whisk
1 cup Epsom Salt
2 cups Baking Soda
1-2 tsp of Essential Oils
Pour the Epsom Salt and Baking Soda into the mixing bowl. Mix until it is well blended together. Slowly pour the essential oils in the bowl mixing as you pour. Then pour the mixture into the mason jar. And you are done.
I personally like to pour 1/2 cup into the tub for each 1/3 of water being filled in it. So 1/3 or the tub filled will get 1/2 cup of bath salt mixture. 2/3 full gets 1 cup of mix. Of course you can add more or less based on your needs.