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Thread: Inconsistent FC results

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    Ksnewman's Avatar
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    Inconsistent FC results

    I tested water this a.m. Using daily test and results were somewhere between 4-5 (deep yellow) which is good but also tested using FAS/DPD and results were about 2.5. The R-0870 is new but the R-0871 was purchased last year so was the R-0600. All stored inside so they don't get too hot.

    Is there something that I am doing wrong or do I just need to adjust IC to produce more chlorine based on drop test

    FC. 4. Or 2.5?
    CC. O
    CYA 60 (need to bring up a bit)
    pH. 7.6
    TA. 70
    Water temp around 78

    I don't want the FC too high but definitely not to low so not sure what I should adjust output based on.

    Thanks!
    18x36 kidney 20,000 gallons IG vinyl. Pentair Easy Touch 8 w/IntelliChlor IC40. Triton II TR100. Pentair Intellifllo Variable Speed. Waterfall/Jump Rock. 2 Pentair Intellibrite lights. TF-100 Test Kit. And a very happy husband who gets to play in the pool without having to take care of it.

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    Mod Squad tim5055's Avatar
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    Re: Inconsistent FC results

    Did you do a CC test when you did the FAS/DPD?

    The FAS/DPD reads FC, the OTO reads TOTAL chlorine. Could you have 1.5 CC? Remember, FC + CC = TC

    Even if your CC is between 0.5 - 1.0 I would say the numbers are close.

    Trust your FAS/DPD numbers
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    Mod Squad jblizzle's Avatar
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    Re: Inconsistent FC results

    The yellow matching is pretty difficult, trust the FAS-DPD.

    And it appears it is a good bit low based on your CYA level.
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    Ksnewman's Avatar
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    Re: Inconsistent FC results

    Quote Originally Posted by jblizzle View Post
    The yellow matching is pretty difficult, trust the FAS-DPD.

    And it appears it is a good bit low based on your CYA level.
    Thanks, that was what I was thinking. Bumping IC output up to get to at least FC of 4
    18x36 kidney 20,000 gallons IG vinyl. Pentair Easy Touch 8 w/IntelliChlor IC40. Triton II TR100. Pentair Intellifllo Variable Speed. Waterfall/Jump Rock. 2 Pentair Intellibrite lights. TF-100 Test Kit. And a very happy husband who gets to play in the pool without having to take care of it.

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    Richard320's Avatar
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    Re: Inconsistent FC results

    My experience, based on comparing the two tests, is that anything between 4 and 7 looks like 5 on the OTO test.

    So what's it good for? Right now, I'm in the enviable position where minimum FC is 4... So as long as the OTO test looks at least as dark as the highest color sample, I'm good.
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    Ksnewman's Avatar
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    Re: Inconsistent FC results

    Quote Originally Posted by Richard320 View Post
    My experience, based on comparing the two tests, is that anything between 4 and 7 looks like 5 on the OTO test.

    So what's it good for? Right now, I'm in the enviable position where minimum FC is 4... So as long as the OTO test looks at least as dark as the highest color sample, I'm good.
    I very seldom use the OTO and just use FAS/DPD but this morning thought I would do both and compare as I had been checking levels,with OTO this week. I won't say I am paranoid about an algae outbreak but I really do not have the time to deal with it if it should happen . All that to say, the low reading on the FAS/DPD and normal on the OTO caused me to have an "uh oh" moment as 2.5 was not what I was hoping for. I do try to keep 4-5 based on current CYA. So, I guess the conclusion is trust the FAS/DPD.

    Thanks!
    18x36 kidney 20,000 gallons IG vinyl. Pentair Easy Touch 8 w/IntelliChlor IC40. Triton II TR100. Pentair Intellifllo Variable Speed. Waterfall/Jump Rock. 2 Pentair Intellibrite lights. TF-100 Test Kit. And a very happy husband who gets to play in the pool without having to take care of it.

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