Hi! hope everyone is having a great summer. I would like to know if someone has some insight as to what can cause chlorine levels to drop so fast within hours. Here is the scenario. This past Saturday, at 10 am my FC was 5.5 ppm. My 2 kids (4 and 8), my wife and I started using the pool around 2pm and stop around 6 pm. Pool water was around 85 degrees and the air temperature around 85-90 degrees. When I tested the water this morning it was 2ppm. I am puzzle, as I did not think FC could be decrease so fast, especially when my salt chlorinator is working properly and ran as per schedule from 8pm to 5 AM. There was no storm/rain that night or anything I can think could cause such a significant decrease on my FC level. Any advice would be appreciated. Thanks.