Where did my bleach go?

[MITBeta]

It sounds like you are adding bleach and then waiting many hours to check... as long as overnight. Have you added and checked after 30 minutes? Have you done a true ONCL test? From what you said above it sounded like you tested, added bleach, but then didn't retest until the morning. You need to test after you add bleach, then wait 8 hours and test again.

Overnight Chlorine Loss Test

 

[SteveK52]

Yes, see results of the OCLT posted above.

 

[MITBeta]

It wasn't clear from what you posted above that you had done the test correctly since you said you expected a higher result given the amount of bleach you added.

If you suspect bad bleach, run the test I suggested above.

 

[SteveK52]

I'm not sure what could be clearer, I ran that test and posted the results. Please read my post on page 1.

 

[MITBeta]

OCLT results 5.5 at night 5 in the morning.
I was expecting a higher FC after adding 81 oz of

This is what wasn't clear. Were you expecting the original 5.5 to be higher or the 5 in the morning to be higher?

Either way, either something is consuming your chlorine, which you can test for, or your chlorine is bad, which you can test for.

 

[Texas Splash]

Steve, I have to admit, after going back to the start of this thread I'm a bit confused, so I better double-check some things. In posts 6-9 you noted doing an OCLT last Friday, but it wasn't clear if the SWG was off. You also mention the SWG running for 12 hours a day, is that day or night? We wanted to confirm no algae last week before adding the conditioner, and you have since added more, so your CYA should be higher. That "should" help your SWG as long as there is no algae. For what it's worth, my pool is slightly less that yours and when I added chlorine manually, it took a 1/2 gallon each day to increase my FC by about 2.5 ppm. Your pool is slightly larger, so you probably need about 3/4 gallon just to kick the FC up about that much.

You seem to still have concerns about the FC level from one day to the next. To do that, we need to be sure if we're monitoring how well the SWG is working, or if there is an algae issue eating chlorine. If the water is crystal and you recently passed the OLCT properly, then that should eliminate algae. Now if you are concerned about the SWG, my suggestion would be to use just enough chlorine to get the FC up to about 6 ppm, leave the SWG on as programmed, do not add chlorine, and monitor the FC. If the FC falls to 4 ppm the next day with just the SWG, increase the output % and/or pump run time to produce more FC. If you don't remember how to calculate how much FC your SWG should produce in 12 hours, the PoolMath can help.

I hope this addressed some of your concerns. Lots of folks hear to help.

 

[SteveK52]

Sorry for any confusion, let me present a timeline.
SWG runs from 8:00 am to 8:00 pm at 65%
SWG appears to be functioning properly (chlorine gas visible at jets)
OCLT test was performed exactly as specified in Trouble Free Pool.
Pool is crystal Clear.
FC checked using Taylors drops.

6/9/2021 FC at 5 (added 65 oz of 7.5% bleach) according to Pool Math that should have brought FC to 7.

6/10/2021 FC at 4.5 (added 81 oz of 7.5% bleach) according to Pool Math that should have brought FC to 7.
CYA was 20

6/10/11/2021 Performed OCLT FC 5.5 at Sunset and 5 at Sunrise

6/11/2021 added 81 oz of 7.5% bleach and 128 oz of liquid CYA

6/12/2021 FC 5

6/13/2021 FC 5.5

If I have missed something please let me know.

 

[Bperry]

OK, tested FC again this morning and the results make no sense to me. FC is 5, no change after adding 81 oz of 7.5% Chlorox bleach with a date of May 20th of this year. .

Be careful of Clorox bleach. It’s gotta be plain bleach with no “stain lifting technology” or ”colormax”, or scented, or anything else.

 

[SteveK52]

Be careful of Clorox bleach. It’s gotta be plain bleach with no “stain lifting technology” or ”colormax”, or scented, or anything else.

Thanks, I'm aware of that and none of the bleach added was anything but plain bleach.

 

[Bperry]

Sorry for any confusion, let me present a timeline.
SWG runs from 8:00 am to 8:00 pm at 65%
SWG appears to be functioning properly (chlorine gas visible at jets)
OCLT test was performed exactly as specified in Trouble Free Pool.
Pool is crystal Clear.
FC checked using Taylors drops.

6/9/2021 FC at 5 (added 65 oz of 7.5% bleach) according to Pool Math that should have brought FC to 7.

6/10/2021 FC at 4.5 (added 81 oz of 7.5% bleach) according to Pool Math that should have brought FC to 7.
CYA was 20

6/10/11/2021 Performed OCLT FC 5.5 at Sunset and 5 at Sunrise

6/11/2021 added 81 oz of 7.5% bleach and 128 oz of liquid CYA

6/12/2021 FC 5

6/13/2021 FC 5.5

If I have missed something please let me know.

One thing I suspect will help is to add the time that you added chlorine and the time you did the test.

 

[SteveK52]

OK, see new timeline including today.
Sorry for any confusion, let me present a timeline.

SWG runs from 8:00 am to 8:00 pm at 65%
SWG appears to be functioning properly (chlorine gas visible at jets)
OCLT test was performed exactly as specified in Trouble Free Pool.
Pool is crystal Clear.
FC checked using Taylors drops.

6/9/2021 FC at 5 (10:00 am) (added 65 oz of 7.5% bleach, 11:00 am) according to Pool Math that should have brought FC to 7.

6/10/2021 FC at 4.5 (10:00 am) (added 81 oz of 7.5% bleach, 11:00 am) according to Pool Math that should have brought FC to 7.
CYA was 20

6/10/11/2021 Performed OCLT FC 5.5 at Sunset (7:30 pm) and 5 at Sunrise (6:00 am)

6/11/2021 (11:00 am) added 81 oz of 7.5% bleach and 128 oz of liquid CYA

6/12/2021 FC 5 (9:00 am)

6/13/2021 FC 5.5 (9:00 am)

6/14/2021 FC 6 (9:00 am)

 

[Bperry]

O6/9/2021 FC at 5 (10:00 am) (added 65 oz of 7.5% bleach, 11:00 am) according to Pool Math that should have brought FC to 7.

6/10/2021 FC at 4.5 (10:00 am)

So if your 65oz actually brought up your FC to 7, that means you only lost 2.5ppm during the day between 6/9 and 6/10? That’s a pretty reasonable amount of FC loss due to sunlight. I was using about 2.0ppm last month and I had to turn my generator up a notch this week cause it was trending downward.

 

[SteveK52]

Not sure what you are referring to, FC dropped from 5 to 4.5 overnight (probably within the error of margin for the test) 7 is where the 4.5 should have been after adding the bleach.

 

[Bperry]

Not sure what you are referring to, FC dropped from 5 to 4.5 overnight (probably within the error of margin for the test) 7 is where the 4.5 should have been after adding the bleach.

Your list says you waited a day after adding the bleach and then doing the FC test. Is that not accurate?

It says you tested on 6/9 at 10am, then again on 6/10 at 10am. You may already know this and the issue is just that the log has a typo in the times, Chlorine is a consumable item that the sun burns off during the day so it’s natural to lose some every day. It’s why you need to keep adding it every day and why adding it only weekly can cause sanitation problems.

If you want to test the concentration of the FC, you will need to perform a test at 10am, add the chlorine at 10:05am, then wait ~30 minutes (Not 24 hours) to test the chlorine again. That way the sun only has 30 minutes to work on it.

 

[SteveK52]

I think what your not seeing is that the SWG is producing enough chlorine to compensate for daily losses, look at the data from the last couple of days where no bleach was added and the SWG output was not changed.

 

[Bperry]

I think what your not seeing is that the SWG is producing enough chlorine to compensate for daily losses, look at the data from the last couple of days where no bleach was added and the SWG output was not changed.

I’m not following what your question is.

If the question is why your FC wasn’t as high as expected the next morning after adding bleach, it could be several reasons:
1. The sun burned off more that day then recent days
2. The pool had something in it that the FC killed and was consumed by.
3. The bleach wasn’t as strong as advertised.

if you want to test the #3 theory, just test it, add bleach, then test again 30min later, not wait 24 hours. All things considered, FC seems to be stable now.

 

[SteveK52]

Thanks for your time.

 

[Bperry]

Thanks for your time.

If I wasn’t helpful, it wasn’t intentional. Maybe someone else will understand better what your asking.

 

[SteveK52]

Bperry,
Thanks again for taking the time to help. This thread turned into something bigger than what I intended with my original post, which was "where did my bleach go". SWG output had been holding its own so when I added bleach I expected to see in increase in FC which I did not. I believe that bleach and subsequnent bleach additions did absolutly nothing making me suspect of the strength of the bleach. I believe data from the past several days proves that. I don't have any of that bleach left to do a test on. I'm ready to move on.