Clear, but no chlorine???

[mary jo]

Oh you must think I'm daft! Yes, FBU got it right: I misunderstood the weekend instructions (diluting at 5:1) to mean continue testing this way until almost done, and since I was going through 50-60+ drops at a time, testing 4-5x a day it made sense….until last night when it occurred to me the exact ppm's lost were getting more critical. That's why I asked about it this morning….I also have been testing each sample more than once to make sure I didn't mis-measure or mis-count.
Good thing I got the 16oz bottle!
From here out I will test at 1:1. I'll post results tomorrow.
I'm sorry about the confusion!

[BigDave]

I don't think you're daft at all. It's on me that I told you to dilute 5:1 and didn't correct that when you received the titrating reagent. I apologize.
The good news is that it appears that a lot of the chlorine demand has been met.
Get a good set of readings for overnight chlorine loss and let's figure out where to go from there.

[mary jo]

BigDave, you are too kind….and most likely a very patient person.

Well, today's results are good and bad I think:
tested last night using 5ml sample. 1 drop = 1ppm

tested @ 11:45pm FC=36 CC=3
tested this morning @ 7:00 FC=35 CC=3

The chlorine loss sounds good, right?
The CC reading of 3 doesn't sound good! (altho I suspect, ahem, it was always testing at around 3 since I failed to multiply the drops added for CC by 6 when I was using a diluted sample…. This one's definitely on me).

So I'm not sure if that changes anything in our approach to getting the pool back in sync.

[BigDave]

Good, keep the shock going. With the 5ml sample test the error is 1ppm so 3ppm is still significant. I don't recall if you have a cover but if you do, leave it open during the day.

[mary jo]

OK- overnight test results are not so good for some reason.
I decided to use the 10ml sample since I now have enough product.
tested last night @ 11:00 FC=35 CC=3

tested this morning @ 7:15 FC=30 CC=3

Is a hiccup like this common? I repeated this morning's test 3 times to be sure.

[CarlD]

Dropping from 33 to 30 overnight? Perfectly normal! when you are super-shocking it's harder to maintain the FC...and you only dropped 9%. I wouldn't worry about that at all.
What I'm wondering is why your CC is so high and not dropping with FC > 30.

PS: I'd run the FAS-DPD test using the 5ml line instead of the ten. If you don't have that line you can either guess where it is or use a kid's med cup that comes with cough medicine with a 5 ml line. Each drop then is 1 full ppm rather than .5. It will take less time to do the test, use half the R-0871, and certainly be accurate enough at those high FC levels.

[BigDave]

I pretty much agree with CarlD, the FC loss is not such a big deal but the CC consistent at 3ppm.
Two questions:
How much bleach did you use yesterday?
Is there any chance that a bromine product has been put in the pool.