This is really weird: I just dumped and refilled (and the tub came up to temp in less that 6 hrs! Happy, happy!) We have really hard water around here, generally. I would have assumed that the calcium content of the water to my house would not change much. It has been 500-550 in the past. Granted, I have only checked it 3-4 times, as I did not expect it to be very variable. Tonight, after filling the tub and letting it get to temp, my Ca level is about 80!!!! What's up with that?
Now, I did add metal gone, but I'm pertty sure I have measured post-dosing before and it has still been high. I guess I should check the tap water. Duh.