Welcome to our forum.
. I'm hoping to avoid draining the tub so soon after my purchase, but if need be, I will for health reasons.
You didn't mention it, but I was curious about cost and checked in my town I pay $13 for 1000 cubic feet of water, which is over 7000 gallons and my tub holds 425 gallons.
Another product that is very similar and a little more mainstream is The Natural.