Ask 'Dr. Spa' Q & A Message Board

No, I don't think you are using too much chlorine, although perhaps you could get by with a little less per use on the days you use the tub multiple times. In fact, it sounds to me like you have a good system going. Off the top of my head, 1 tsp should be about 3ppm in your tub. If you have a measureable residual 12 hours after a dose, and it is 0 at 24 hours, that sounds about perfect. As far as days between doses when unused, every other is safest, but you can probably stretch it a little occasionally. The only way to find out is to try it, and see if the water gets cloudy. What are you using for your weekly shock, and how much of it?