Unexplained rise in FC?

jerseyben · Jun 23, 2022

Hi all, first time poster here! I am new to the TFP method and ditched the trichlor floater this year. I have been pretty diligent testing using the TF-100 kit daily and have been struggling to keep the FC level at the ideal level. Yesterday FC was at 6.5 so I added 2 Gal 10% bleach and 16oz Cal-Hypo this morning. This afternoon at about 3pm I tested using the Chlorine FAS/DPD test and got a reading of 13. At 9pm I tested again and got a reading of 18! I even tested again to double check and again got 18. Can anyone help to explain this rise in FC? Perhaps the Cal-Hypo takes awhile to dissolve?
Thanks!

FC 18
pH 7.5
TA 130
CYA 70
CH 29

Deb04 · Jun 23, 2022

The 2 gallons of liquid chlorine would raise your FC 8 and the pound of CalHypo would raise it about 3 (+ or -, depending on the strength), so that's a total of 11. Kind of makes me think the 13 this morning was a testing error. Certainly there would be some FC loss from yesterday afternoon to today, but if you aren't eating chlorine, only 1 or maybe 2.

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Unexplained rise in FC?

jerseyben

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Deb04

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