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Thread: Does 0.5 CC really not matter?

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    Does 0.5 CC really not matter?

    The BBB ten commandments states that you pass an overnight test with 0.5 CC or less. But is that really passing and it is no different than 0, or does it still indicate an algae problem that is lurking and as a precaution, the pool should be slammed until the CC is down to 0?
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    y_not's Avatar
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    Re: Does 0.5 CC really not matter?

    More than anything, I have always felt it is for margin of error in the test accuracy and repeatability.

    Other than that, there can always be something in the water, however small, for the chlorine to snarf! That's its job, that's what it does. The CCs simply show the byproduct of this process.

    Even just putting your arm in to take the test sample introduces a tiny amount of organic material for the CL to oxidize. Not enough to show up on our test mind you, but it's still bather waste. Just not the equivalency of 1 whole body being in the water. My point is, things build up, every little thing adds to the CL demand load and produces byproducts, those being CCs.

    Beyond that.... well, that's what we have Chem Geek for.
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    Charlie_R's Avatar
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    Re: Does 0.5 CC really not matter?

    I'm not Richard, but here's my take on it:

    Testing errors (we are all human, after all) will account for up to .5 on the 10 ml sample.

    While the drop size from the bottle is consistent when taken as an average, there can be minute differences.

    Another source of this error is the sample size. Unless you have lab equipment that can give you precise samples, there can be slight differences in your sample.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Mod Squad zea3's Avatar
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    Re: Does 0.5 CC really not matter?

    CC of 1.0 or more may indicate a need to slam the pool. There are always organics in your pool and when chlorine oxidizes them it creates CC. Therefore it would not be unusual to have a small amount of measurable CC at any given time. Usually if your CC is 1.0 or more there is something in the water increasing the chlorine oxidation and thus creating more CC. So if you have 1.0 of CC and the water is loosing its sparkle bumping up the chlorine may take care of it, but if it doesn't, its time to slam.
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    Re: Does 0.5 CC really not matter?

    Does the cc test need to be followed by the fc test, or can the cc test be done on a fresh sample? The reason I ask is that my chlorine is high so I want to test fc with a 10ml sample, but for the cc test, I would love to have the more precise results of .2 per drop of the 25ml sample.
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    Jandy DEL 48 DE Filter
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    Taylor FAS-DPD Test Kit K-2006

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    Charlie_R's Avatar
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    Re: Does 0.5 CC really not matter?

    You do understand that doing the CC test is with the same sample you just completed for your FC, right?

    If you want to use up a large amount of your R-0871, go ahead and do it twice with the different sample sizes.

    But for our purposes, the .5 resolution is close enough.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Re: Does 0.5 CC really not matter?

    Yes, I've always tested cc with the fc results, I was just wondering if there was a way to switch sizes mid-stream. I actually bought a pint of R-0871 because even though it may go bad before I finish it, it was worth it for me to splurge and never have to feel that I'm being cheap on testing. Still, it is easier to test an fc of 9 with 18 drops instead of 46.
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    30K Gallon Vinyl Inground
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    BBB Method
    Taylor FAS-DPD Test Kit K-2006

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    Re: Does 0.5 CC really not matter?

    There is no way to test the CC without testing the FC first in the FAS-DPD kit so yes, it takes a bunch of reagent to test since you do FC first.

    As for the 0.5 ppm limit, that's mostly because we normally recommend using a 10 ml sample size so one drop represents 0.5 ppm. Your actual CC is likely to be less. If you use a 25 ml sample size so that each drop represents 0.2 ppm, you will probably find that the pink is cleared in just one drop meaning you have <= 0.2 ppm CC or sometimes <= 0.4 ppm CC. Neither is a problem.

    The CC is more of a secondary indicator to tell you about things you don't see in the pool. The primary indicator is seeing dull/cloudy water or visible algae. Another good indicator is the overnight chlorine loss test. You can have algae in the pool and not a high CC and vice versa. Usually the highest CC is seen when there is ammonia in the pool and you add chlorine to it such as when bacteria convert CYA into ammonia if you let the pool go (i.e. FC get to zero).

    In short, don't stress out about the CC. Just test for it when you normally test your FC and don't worry if you have some pink that goes away with one drop using a 10 ml water sample.
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