I ran a test with the TF-100 kit on my pool water 3 days ago. Everything looked pretty good with just a little low pH of 6.9, and the FC was at 8.0. I ran another test last night to test the FC again and the test water wouldn't even turn pink after adding the powder in and mixing it. I also added some borax (per Pool Math) to get the pH up a bit and it's now right around 7.8.
As a new pool owner, I'm confused as to how I could lose chlorine that quickly in just 3 days. Is this normal, or am I missing something?
Here are my test results from 3 days ago:
CH - 225
TA - 50
CYA - 40
pH - 6.9