I've been using dilution testing for FC/CC and CYA.
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I've been using dilution testing for FC/CC and CYA.
You are diluting the sample for the FAS-DPD test? If so, please don't dilute it more than 1:1. Yes, it will take alot of R-0871 - you might want to order a 2oz bottle. You are getting close to the end and I'm concerned that a 5:1 dilution might be skewing your measurments.
Why would you use dilution for the FAS-DPD test (head scratch) ?
Merely fill to the 5ml line (or halfway to the 10ml line if you don't have a 5ml line) and count 1 drop = 1ppm of FC.
@CarlD: I have a cylinder I use for testing that has a 5ml line (I suspect you do too) from a different kit. The K2006 comparator starts at 10ml.
@mary jo: Perhaps you have another vessel that can measure 5ml. The dose cups from children's medicine comes to mind.
You intended those instructions for the weekend only (when she was out of 0871).Quote:
Originally Posted by BigDave
Also, I believe she bought the 16oz bottle so she should be good even with the 10ml sample.
If not, Mary Jo, I still have an extra 2oz bottle of 0871 if you need it. I am leaving for VA Saturday morning so you would need to let me know today.
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!
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.
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.
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.
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.