Chlorine keeps rising

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R

rtv

0
May 20, 2015
11
Tampa, FL
I have a 18000 gallon in ground vinyl pool and use the Taylor test kit.
Lately my chlorine level keeps rising for no apparent reason, I have not added any type of bleach or chlorine.
I have also seen an ALK drop but PH has remained at 7.5

My readings have been like this:

9/16/17
FC=8.5
CC=0
TC=8.5
ALK=80

9/24/17
FC=9.5
CC=.50
TC=10.0
ALK=60

10/2/17
FC=12.5
CC=.50
TC=13.0
ALK=60

CYA stays between 35-40

I cant understand why the CH keeps rising. The pool is in the hot FL sun but it doesn't appear to be being used up.
I use the 4 in 1 Trichlor tabs in the chlorinator, there were 3 in there on 9/16, since not adding any there is now just 1 in the chlorinator.
Could those tabs dissolving keep raising the chlorine level like that and also be responsible for the drop in ALK?

I have had this pool for many years and have never seen the chlorine keep increasing like this.
 
The only way the FC is rising is because you are adding chlorine. Although there is no way that only 2 tablets would have maintained the FC level for 2 weeks and raised the FC level by 4ppm ... that is just impossible.

Tablets are acidic so they will lower the pH and TA.

You sure you do not have a SWG on the pool also or something else adding chlorine? What you have posted is not chemically possible.
 
I am not an expert on pool care, but i will give you my thoughts.
Since your using trichlor as your source of chlorine i would think the rise in fc would be cause od the slow release of the tablets.
I am also surprised that your cya is as low as it is and not through the roof. Maybe someone with a lot more experience will chime in.
 
jblizzle said:
The only way the FC is rising is because you are adding chlorine. Although there is no way that only 2 tablets would have maintained the FC level for 2 weeks and raised the FC level by 4ppm ... that is just impossible.

Tablets are acidic so they will lower the pH and TA.

You sure you do not have a SWG on the pool also or something else adding chlorine? What you have posted is not chemically possible.
Click to expand...
________________

No, I do not have a SWG and I am the only one who takes care of the pool.
The CYA has always stayed pretty constant at the 35-45 level.

The pool water looks very good, very clear with no signs of any algea.
I have considered a partial drain and refill but even the rain has not lowered it.

The regents I use for testing are only a few months old but is it possible the chlorine regent is bad and giving me incorrect readings?
I ran the chlorine test multiple times but get the same results.
 
rtv said:
I have a 18000 gallon in ground vinyl pool and use the Taylor test kit.
Lately my chlorine level keeps rising for no apparent reason, I have not added any type of bleach or chlorine.
I have also seen an ALK drop but PH has remained at 7.5

My readings have been like this:

9/16/17
FC=8.5
CC=0
TC=8.5
ALK=80

9/24/17
FC=9.5
CC=.50
TC=10.0
ALK=60

10/2/17
FC=12.5
CC=.50
TC=13.0
ALK=60

CYA stays between 35-40

I cant understand why the CH keeps rising. The pool is in the hot FL sun but it doesn't appear to be being used up.
I use the 4 in 1 Trichlor tabs in the chlorinator, there were 3 in there on 9/16, since not adding any there is now just 1 in the chlorinator.
Could those tabs dissolving keep raising the chlorine level like that and also be responsible for the drop in ALK?

I have had this pool for many years and have never seen the chlorine keep increasing like this.
Click to expand...
In your 18000 gallon pool, one 8oz trichlor tab adds 3ppm to FC & 1.8ppm to CYA. Three tablets, once completely dissolved, will have added over 5ppm to CYA making it impossible for your CYA to remain static at 35-40ppm, unless you have a leak and are adding a good amount of water every day.

Even if your pool is only using 2ppm of FC daily, there is no way you would go 16 days on 9ppm of FC (3ppm FC each X 3 tabs), let alone see rising FC levels.

As Jason has already stated, this is chemically impossible.

Which test kit are you using, and how old are the reagents?
 
domct203 said:
In your 18000 gallon pool, one 8oz trichlor tab adds 3ppm to FC & 1.8ppm to CYA. Three tablets, once completely dissolved, will have added over 5ppm to CYA making it impossible for your CYA to remain static at 35-40ppm, unless you have a leak and are adding a good amount of water every day.

Even if your pool is only using 2ppm of FC daily, there is no way you would go 16 days on 9ppm of FC (3ppm FC each X 3 tabs), let alone see rising FC levels.

As Jason has already stated, this is chemically impossible.

Which test kit are you using, and how old are the reagents?
Click to expand...


I use the Taylor test kit and the regents about 3 months old.
After rechecking my records I see that I added 3 chlorine tabs after the 9/24 chlorine test since the chlorinator was down to 1 tab at that time.
I guess I must assume the 3 chlorine tabs caused the increase but its still the first time I have experienced this.
I am guessing the only way to get it lower is by a partial drain and refill with fresh water.
 
rtv said:
I use the Taylor test kit and the regents about 3 months old.
After rechecking my records I see that I added 3 chlorine tabs after the 9/24 chlorine test since the chlorinator was down to 1 tab at that time.
I guess I must assume the 3 chlorine tabs caused the increase but its still the first time I have experienced this.
I am guessing the only way to get it lower is by a partial drain and refill with fresh water.
Click to expand...
If you are referring to FC, it will come down on it's own, don't add any chlorine for a day or two. Just be sure to check to make sure it doesn't go too low.

You should re-check the CYA, as that does not quickly 'dissipate' like the FC does. Are you checking CYA outdoors on a bright sunny day, back to the sun, viewing the vial at about waist level?
 
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