Apparent Paradoxical increase in Free Chlorine

[Bcorig]

The Water temperature is 51 degrees. The Salt Water Generator has been off since November (red light) (And besides it is an old generator I install during the winter to spare the functioning one).
Anyway Feb 4 Total Chlorine=4.5 for which I added 96 oz of 6% liquid chlorine (Pool Math® using the Liquid Chlorine CL/CYA chart Goal = 8 with CYA = 60) pH 8 (22 oz 32% muriatic acid) T-Alk 70 and CYA 60
Today Feb 10 Total Chlorine=9 pH 8 TA 70 Assume CYA 60 from last week CC = 0
There has been no rain, and if anything the average daily temperature has been slightly higher (H 70 L 40) and it has been sunny for the past 6 days (my solar panel generation attests to that)
I triple checked the result using 10 mL volume using Taylor.
I assumed that after correcting the chlorine to 8 last week it should decline on a daily basis. I didn't expect to see a higher value give or take 1 ppm.
I also assume I'm missing something obvious here - that's been known to happen.
Aside from daily checks unit Cl is needed and then checking the level a day after correction, any other suggestions?
The water level is the same - none added.

 

[Rancho Cost-a-Lotta]

Are you sure the SWG is switched off and not functioning? Our climate is similar and my water temp is up to 59 degrees (this afternoon), high enough for my SWG to function. Is it possible your SWG operating.

My pool has been consuming about 1 ppm of FC every two to three days.

Otherwise, testing error or the chlorine fairy has been busy

 

[ajw22]

We have no way of confirming the accuracy of your FEB 4 FC test or the exact amount or strength of the chlorine you added. You did not test 30 minutes after the chlorine addition to record the actual amount of FC you have.

You could have a testing error, a chemical error, or a
PoolMath error. If you care then test after you add a chemical and see what the actual result is.

I would just move on.

 

[Methuselah]

I'd have to do the math to know if scaling is reasonable, but I suppose if you really wanted to know, you could dose a gallon of distilled water, measure it, and compute your percentage?

I did something like that once with some Kroger's branded that seemed weak, I think it was 2 1/2 or 3% result, no bargain!

 

[Bperry]

The Water temperature is 51 degrees. The Salt Water Generator has been off since November (red light) (And besides it is an old generator I install during the winter to spare the functioning one).
Anyway Feb 4 Total Chlorine=4.5 for which I added 96 oz of 6% liquid chlorine (Pool Math® using the Liquid Chlorine CL/CYA chart Goal = 8 with CYA = 60) pH 8 (22 oz 32% muriatic acid) T-Alk 70 and CYA 60
Today Feb 10 Total Chlorine=9 pH 8 TA 70 Assume CYA 60 from last week CC = 0
There has been no rain, and if anything the average daily temperature has been slightly higher (H 70 L 40) and it has been sunny for the past 6 days (my solar panel generation attests to that)
I triple checked the result using 10 mL volume using Taylor.
I assumed that after correcting the chlorine to 8 last week it should decline on a daily basis. I didn't expect to see a higher value give or take 1 ppm.
I also assume I'm missing something obvious here - that's been known to happen.
Aside from daily checks unit Cl is needed and then checking the level a day after correction, any other suggestions?
The water level is the same - none added.

Are you sure it was 6% liquid chlorine? Most of the hardware store stuff is 10% or 12.5%.

 

[Bcorig]

We have no way of confirming the accuracy of your FEB 4 FC test or the exact amount or strength of the chlorine you added. You did not test 30 minutes after the chlorine addition to record the actual amount of FC you have.

You could have a testing error, a chemical error, or a
PoolMath error. If you care then test after you add a chemical and see what the actual result is.

I would just move on.

Sorry for the delay in response. I discovered I was using the 6% default for the liquid chlorine on PoolMath instead of the actual 12.5%. I was shocking the pool every two weeks. I never tested thirty minutes afterward either (will do so today).
Thanks. I KNEW it would be something obvious.

 

[Bcorig]

Are you sure it was 6% liquid chlorine? Most of the hardware store stuff is 10% or 12.5%.

You are correct. PoolMath is set to 6% but, as you said, the liquid I am using is 12.5%. I miscalculated the amount needed, was shocking the pool every two weeks. God only knows what the level was after I added because I only checked.
I thank everyone for their responses.

 

[Jimrahbe]

B,

Why are you "shocking" the pool every two weeks???

Thanks,

Jim R.

 

[Bcorig]

B,

Why are you "shocking" the pool every two weeks???

Thanks,

Jim R.

It was unintentional.
Week 1: Chlorine = 4. I over calculated the Chlorine demand based upon 6% concentration of chlorine solution instead of 12.5% (50%).
Week 2: Chlorine = 9. None needed.
Week 3: Down to 4 again. So, I would calculate the amount needed based on 6% and the cycle would repeat.
Week 4: Up to 9 again.
I suspect that 30 minutes after adding the chlorine in these amounts the level was 18 or so. Hence I used the expression “shocked”.
Today the level was 6. I calculated using the correct concentration, added, and rechecked the level and it was at the desired goa.
Dumb. Really dumb.