Sorry, I'm using a little chlorine in the tub now 1 teaspoon after I get out. I read yesterday that chlorine can leach out the iodine. I tried bromine, but the same thing, plus it causes me to itch. So I'm looking for something for the tub to kill bacteria, that won't ruin the tub. Their is copper products, but dangerous to the trees when I drain it. I live in the country and have a septic tank, can't put it there. My hot tub is one of the few vices I have left, and don't really want to give it up. I'm 66 and tried for many years to destroy my body with skydiving (old round chutes), and snow skiing as fast as I could go. Lots of crashing and burning in my life. A few motorcycle crashes to. I thought if I made a gallon of silver and put it in that would do it. Thanks.