Chlorine level dropped significantly in a week?

[Frank in FL]

For the past 2 months I’ve been maintaining between 4-6 ppm of chlorine. The rest of chem levels were on point. During this time the temps here in Florida were around 95 deg.

Within the last week, the temps have dropped to around 70 at night and a high of around 85 +\- during the day. There also has been no rain and the sky has been slightly cloudy.

Today I measure my chem levels and my chlorine was at 2.0. Rest of chem levels were fine ?‍

Pool runs from 8am-6pm at 90% for the salt cell. Then at 9pm-5am without the salt cell activated.
I’m lost as to how my chlorine has gone down that much.

 

[mknauss]

Have you checked your CYA level recently?

 

[Frank in FL]

Yes checked all levels today and all was good except for the chlorine.
CYA has been a constant 75

 

[mknauss]

Very odd to have no CYA degradation at all with elevated water temperatures.

 

[Frank in FL]

The water temperature declined within the last week. It’s been a constant 87-90 deg up until a week ago when the temps started to drop into the 80s