Welcome to our forum.
There are basically 3 systems.Chlorine, Bromine and Baqua. Baqua is supposed to be easiest but costs the most and I think is finiky if something were to go out of wack.A lot of people use bromine and by what they say it seems easy. But chlorine (dichlor) is probably the cheapest, but it does take more work of adding dichlor after using the tub and every so often if you don't.People use and like all 3 ways ... it's really up to you to find what works best for you.