If you need to shock the water (quick sanitizer boost) then use non-chlorine shock a.k.a. MPS (Monopersulfate). This will oxidize organics and because of that assist the chlorine to do a better job. You can best add some after using the hot tub or if you haven’t used the hot tub just add some once a week. You can add about 30-60 gram or 1-2 ounces on these occasions. If you still run into issues click here for some additional help and learn about the different sanitizers and what chemical will help.