No Combined Chlorine, FC 7-9, CYA 35? Taylor test vs pool store?

[InheritedAnthony]

Hi!
I took some pool water to test at my local store and the numbers came back puzzling to me, so I tested at home with the Taylor kit and I'm still unsure I fully understand.

1. If I have a decent CYA, shouldn't the there automatically be combined chlorine if the free chlorine is over a certain %?
2. Are these Difference between the pool store and my results too much, an if so who's is right?
   • I am not sure what test system they use. (It's not a branded chain)
   • My reagents are from last year as I did not run out.
3. (Is it common for CH to drop fast? Mine dropped from 425 to 275 over 9 days.)
   • I do have a leak that I'm trying to fix, but that's for another post.

Here are the 2 tests - pool store and mine with the Taylor kit and speedstir:

TEST	Store	Taylor
Alk	90	60
PH	7.3	7.5
TC	9	7
FC	9	7
CC	0	0
TH	300	275
CYA	45	35

I'm also not sure how to read the CYA view tube - here are 2 photos at 40 and 30 ppm, in the shade, mid-afternoon on a cloudy day:


Here's the test:

 

[Bperry]

Hi!
I took some pool water to test at my local store and the numbers came back puzzling to me, so I tested at home with the Taylor kit and I'm still unsure I fully understand.

1. If I have a decent CYA, shouldn't the there automatically be combined chlorine if the free chlorine is over a certain %?
2. Are these Difference between the pool store and my results too much, an if so who's is right?
   • I am not sure what test system they use. (It's not a branded chain)
   • My reagents are from last year as I did not run out.
3. (Is it common for CH to drop fast? Mine dropped from 425 to 275 over 9 days.)
   • I do have a leak that I'm trying to fix, but that's for another post.

Here are the 2 tests - pool store and mine with the Taylor kit and speedstir:

TEST	Store	Taylor
Alk	90	60
PH	7.3	7.5
TC	9	7
FC	9	7
CC	0	0
TH	300	275
CYA	45	35

I'm also not sure how to read the CYA view tube - here are 2 photos at 40 and 30 ppm, in the shade, mid-afternoon on a cloudy day:
View attachment 603881View attachment 603882

Here's the test:
View attachment 603885

you cant trust anything that came from the pool store. They just dont test reliably. For your questions:
1. No
2. Taylor kit is more accurate.
3. Not possible unless nearly 1/2 the water was replaced with distilled water.

 

[ajw22]

We always round CYA up. Call your CYA 40ppm and move on.

 

[InheritedAnthony]

you cant trust anything that came from the pool store. They just dont test reliably. For your questions:
1. No
2. Taylor kit is more accurate.
3. Not possible unless nearly 1/2 the water was replaced with distilled water.

Thank you.

Regarding the chlorine:
So how do I get some CC instead of just free chlorine?
I thought that the equilibrium will have the CYA will "Lock" a certain amount of the available chlorine depending on the amount of CYA, so shouldn't some of the FC be held by the CYA?

Regarding the Calcium: I guess I either did a test wrong or perhaps too soon after adding calcium chloride after refilling a bunch of the pool?
I'll just test again in a few days and confirm that it settled down

 

[Donldson]

So how do I get some CC instead of just free chlorine?

CC is the byproduct of chlorine oxidizing certain chemicals. Your target for it is zero.

 

[Bperry]

Thank you.

Regarding the chlorine:
So how do I get some CC instead of just free chlorine?
I thought that the equilibrium will have the CYA will "Lock" a certain amount of the available chlorine depending on the amount of CYA, so shouldn't some of the FC be held by the CYA?

Regarding the Calcium: I guess I either did a test wrong or perhaps too soon after adding calcium chloride after refilling a bunch of the pool?
I'll just test again in a few days and confirm that it settled down

As said above, the goal is zero CC. Theres nothing locked or an equilibrium to worry about.

 

[InheritedAnthony]

Oh, right.
Thank you all!