Can a huge rain storm drop my CYA from 55/60 to 35?

[debmar]

Went away for a day and did not add chlorine yesterday and there was a huge rain storm that gave us a few inches. My CYA really dropped and my CC is up at 2.0 .. should I be okay just adding my chlorine? Pool water looks amazing.
FC 2.0
CC 2.0
PH 7.6
TA 90
CYA 35

 

[ajw22]

Given the variability in CYA testing a 10 point swing is not unusual. CYA 40 is fine for you. You can add 10 ppm if you want.

We round up CYA so if the dot disappears between 40 and 30 you call it 40. There is no 35 or 55 readings.

 

[debmar]

Given the variability in CYA testing a 10 point swing is not unusual. CYA 40 is fine for you. You can add 10 ppm if you want.

We round up CYA so if the dot disappears between 40 and 30 you call it 40. There is no 35 or 55 readings.

 

[debmar]

Given the variability in CYA testing a 10 point swing is not unusual. CYA 40 is fine for you. You can add 10 ppm if you want.

We round up CYA so if the dot disappears between 40 and 30 you call it 40. There is no 35 or 55 readings.

Okay, lol, so 40 it is. I'm kind of happy about this because I will use less liquid chlorine and when I go on vacation in a few weeks I can use some pucks and not have to worry too much about the rise with the CYA... I think I'm right about this.

 

[debmar]

With the CC at 2.0 do I need to be concerned and think about a slam... am I right if over 2.5 is when I need to do a slam? Thank you

 

[ajw22]

Do an Overnight Chlorine Loss Test

FC of 2 is below the minimum for CYA 40. See FC/CYA Levels. You could have picked up some algae. Definitely raise up your FC to 7.

If your pool is clear a SLAM Process should be quick.

 

[debmar]

Yes, I've been following that chart and saw that it was below. I will rise to 7 and I will do the slam tonight. Thank you