OK- it was actually a 5ppm drop (35 down to 30). Did I wait too long to take the morning test? (should I test before sunrise ~ 6:00?) Yesterday is was overcast and rainy all day. This morning it's sunny.

I added 1 1/2 jugs yesterday. Yesterday morning's initial reading was 35 so I didn't need to add much to keep it at 30. I added the last jug @ 9:00 and tested at 11:00 and got 35.

Not sure what bromine is, but the only chemicals ever put into my pool this season: pH up (about 15 lbs), phos-free (1.4L) and 3" chlorine tablets for the inline chlorinator.