Opening Chlorine Reading of 12.5 ppm??

[DonW]

We closed the pool last year on Oct. 5th., and according to my journal the readings were:
FC 27
TC 27
CC 0
PH 7.6
TA 250
CYA 80

Opened this morning and on a lark took a water sample and got the following:

FC 12.5
TC 13
CC 0.5
PH 7.7
TA 250
CYA 60

(I'm going to address the high PH reading.)
Is it truely possible that we still have 12.5 FC residual? I expected zero, and CYA dropped 20????? (Super sunny today, might have a bearing on the 20 unit loss compared to an October day). I can smell the chlorine in the test sample!
O.K., the reagents are from last year, but the DPD powder and the FAS-DPD reagent should have a shelf life of 2 years. Just wanted to express my surprise and wonder if anyone else has experienced this residual chlorine "phenomenon".

 

[duraleigh]

I would say more and more members are reporting residual chlorine. It's a good indicator you had a nice clean pool that was well maintained and closed properly.....Nice work! :lol:

YOur pH is in a "normal" range but your TA is fairly high. If both remain pretty stable this season, I would suggest leaving them both alone. If your pH climbs continually, look into reduce your TA down to around 100ppm.

 

[Melt In The Sun]

Chlorine will break down CYA, very slowly. I never closed and kept FC in the pool the whole time, and 20 ppm loss is the same as what I saw over the winter.