I just inherited a 450 gallon hot tub w/ an ozonator built in. I did lots of reading on here (thank you so much!) and I have been using dichor after each soak (2-3 bathers/ 2-3 times/week) and a weekly shock of MPS. Everything is fine except that the the FCL seems to decrease pretty rapidly (perhaps due to the ozonator?). I would like to limit the use of the chlorine and put in a Nature2 stick. Here is my question: How do I monitor sanitization with the Nature2 in there? My guys at the store say that I don't need to! Will the chlorine hang around and catch anything the Nature2 doesn't sanitize? Is FCL still the best way to monitor?
I apologize if this question has been answered before, but I have done my best to search for it!