FC Doesn't React Linearly?

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M

manfacro

0
Jul 9, 2018
90
Davenport, FL
Hi all,



Working on getting my daily/weekly process figured out after switching to LC, so I've been doing daily FC checks to watch the drop and figure out how much LC I need to add daily/every other day. My problem is the trend has changed from 4ppm a day to 1ppm a day drop. See trend below....

08/13/18 10:31 AM13
08/12/18 11:17 AM14.5
08/11/18 11:39 AM15
08/10/18 2:28 PM19.5
08/09/18 11:06 AM23

Is this typical? My CYA is 70 so my target is 8-10. My thought process was I'm waiting till I hit 9ppm, then add in 4 cups a day to bring it up 4ppm (per pool math). But that doesn't work if I loose a significant portion less than other days. The reason the FC was/is high right now is because when I switched to LC I brought it up to Shock level to see if Pool Math was accurate to my pool gallons for dosing with LC (it's pretty close!), but within the time in the chart, no FC was added.


Thanks for any insight!



--Dan
 
The FC loss to sunlight is a percentage more than a number. So as you have higher FC you will have higher net loss of FC per day.

Let your FC fall closer to your target level for CYA and then see what your loss is. It will vary each day, but an average will be somewhere in the 2-4 ppm per day range.
 
Figure you'll lose somewhere between 2 and 4 ppm per day. Less than 2 means you have a cover or something,. more than 4 means you've got a problem somewhere, whether its algae or someone with a weak bladder...

But linear losses are no. It's, as stated above, more of a percentage, with some related-rates calculus thrown in just to make it more confusing. Half-life might be more descriptive. At any rate, it's a shame that FC losses aren't linear, or a person could just pour in a week's worth once a week and be done with it. Or two weeks' worth before vacation.... who cares if it goes beyond shock level -- no one;s home to go swimming in it anyway! Get used to the daily dump. It won't be long before it gets as mindless and routine as brushing your teeth before bed.
 
Not much. The bulk of FC loss is due to sunlight. Covered/indoor pools have little FC loss.
 
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