Chlorine dropped 5 PPM in 24 hours

[willmclaughlin07]

I just finished slamming my pool a few days ago using 10% liquid chlorine. I tested it using a TF100 yesterday evening my FC was at 5.5. I just tested again this evening and my FC was at .5. Below are the full test results as of this evening:

FC: .5 ppm
PH: 7.2
CYA: 30 ppm
TA: 70 ppm
CH: 875 ppm
Water temp: 87 degrees

I know my CYA is a little low but would that cause such a significant loss in 24 hours?

 

[ajw22]

Welcome to TFP.

Do a Overnight Chlorine Loss Test with your FC at 6 to 8.

 

[reggiehammond]

CYA 30 with the excessive heat we've had and full sun can easily lose 3-4ppm. More if any one is swimming as well.

 

[Bperry]

I just finished slamming my pool a few days ago using 10% liquid chlorine. I tested it using a TF100 yesterday evening my FC was at 5.5. I just tested again this evening and my FC was at .5. Below are the full test results as of this evening:

FC: .5 ppm
PH: 7.2
CYA: 30 ppm
TA: 70 ppm
CH: 875 ppm
Water temp: 87 degrees

I know my CYA is a little low but would that cause such a significant loss in 24 hours?

Did you add any chlorine today? The sun eats 3-4 per day.

 

[willmclaughlin07]

Ok. Yes I added after I tested it. I am going to add a SWG. I am looking at the Pentair IC40 because I already have the Pentair automation system. Would this be a good fit for my pool size (12,000 gallons)?

 

[Bperry]

Ok. Yes I added after I tested it. I am going to add a SWG. I am looking at the Pentair IC40 because I already have the Pentair automation system. Would this be a good fit for my pool size (12,000 gallons)?

Yea, at least twice as big as your pool volume is the recommendation.