I had to start a separate thread on this.
Friday, fresh water fill (from a well) after ahh-some, drain, clean, refill, drain, clean, refill.
Adding 1oz dichlor, FC after 20 minutes was 9.0 (at 11pm)
Checked yesterday, 2pm FC was 7.4ppm. Reasonable loss I think
Checked today at 5:30pm, FC = 3.8ppm
Haven't been in it since we drained and filled so no bather waste.
What the heck would eat more chlorine in the last 28 hours than in the prior 15?
This just seems weird to me.