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Thread: My FC is off the chart - Help!

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    My FC is off the chart - Help!

    My pool is 33,000 gallons, vinyl liner, 20 X 40. The water looks great but after testing the water with my taylor tester, the chlorine test was orange - off the chart. When I tested the chlorine with 087 powder, it was 25. The pool store said the FC was 10 - which makes sense (that the water looks great) since the CYA is 100. According to my testing it is 90.
    FC - off the chart
    CC - 0
    CYA - 90
    PH - 7.6
    TA - 100
    I use trichlor pucks in an auto chlorinator- which has been turned off for three days. We had 1 day of heavy rain and I added (a small amount of water), but only a slight change in chlorine. I know I have to get the CYA down to at least 50 and chlorine down to 5. This has never happened before. We have a new chlorinator and had it set too high for 1 day, but did not expect to see chlorine so very high. I can't remember seeing the test turn orange even after shocking.
    Any ideas of what could have caused this or suggestions to get the chlorine down?
    20 X 40 lazy L, vinyl liner, chlorine, approximately 33,000 gallons, automatic chlorinator, DE filter, HP 1.5 variable pump, dolphin Triton cleaner
    cleaner

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    needsajet's Avatar
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    Re: My FC is off the chart - Help!

    Welcome to TFP! Good to have you here

    If you're planning to reduce CYA, you can reduce CYA and FC with the same water exchange.

    You can reduce FC alone with sodium thiosulfate available at the pool $tore. Hydrogen peroxide is another option.

    Let's talk about a switch to chlorinating liquid! What test kit do you have?
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: My FC is off the chart - Help!

    Quote Originally Posted by needsajet View Post
    Welcome to TFP! Good to have you here

    If you're planning to reduce CYA, you can reduce CYA and FC with the same water exchange.

    You can reduce FC alone with sodium thiosulfate available at the pool $tore. Hydrogen peroxide is another option.

    Let's talk about a switch to chlorinating liquid! What test kit do you have?
    My Taylor kit is TF - 100. I use pucks or liquid chlorine, depending on the CYA. Just tested and the FC came down to 17, CYA is 70, TA is 100, PH is low @ 7.2. Since I don't want to add sodium thiosulfate, I guess I need to be patient. UGH!
    20 X 40 lazy L, vinyl liner, chlorine, approximately 33,000 gallons, automatic chlorinator, DE filter, HP 1.5 variable pump, dolphin Triton cleaner
    cleaner

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    Re: My FC is off the chart - Help!

    Patient to do what? The pool is perfectly swimmable with FC of 17 ppm.

    Continued use of the pucks will drive your CYA right back up to an unmanageable level.

    How did you reduce CYA from 90-100 to 70 ppm?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    needsajet's Avatar
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    Re: My FC is off the chart - Help!

    Yeh, no UGH required, jump in!!

    Looks like the trichlor made the pH drop as well. Keep an eye on that, but it should rise with a bit of swimming and no more trichlor. Can't understand how your CYA went down unless that was a lot of rain and it was pumped out or went to overflow.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: My FC is off the chart - Help!

    Quote Originally Posted by duraleigh View Post
    Patient to do what? The pool is perfectly swimmable with FC of 17 ppm.

    Continued use of the pucks will drive your CYA right back up to an unmanageable level.

    How did you reduce CYA from 90-100 to 70 ppm?
    Thanks for the good news. I thought the FC should not be above 8 with CYA of 70. We did have a lot of rain on Friday /Saturday overnight. Maybe I didn't test it correctly yesterday. But the water is crystal clear. I don't plan on using pucks with the high CYA.

    - - - Updated - - -

    Quote Originally Posted by needsajet View Post
    Yeh, no UGH required, jump in!!

    Looks like the trichlor made the pH drop as well. Keep an eye on that, but it should rise with a bit of swimming and no more trichlor. Can't understand how your CYA went down unless that was a lot of rain and it was pumped out or went to overflow.
    We did have a lot of rain on Friday /Saturday overnight. Maybe I didn't test it correctly yesterday. But the water is crystal clear. I don't plan on using pucks with the high CYA.

    - - - Updated - - -
    Last edited by keagle; 07-03-2016 at 10:19 AM. Reason: posted 2x. New and not sure what I'm doing :)
    20 X 40 lazy L, vinyl liner, chlorine, approximately 33,000 gallons, automatic chlorinator, DE filter, HP 1.5 variable pump, dolphin Triton cleaner
    cleaner

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    needsajet's Avatar
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    Re: My FC is off the chart - Help!

    The pool is safe for swimming when:
    You can clearly see the bottom of the pool at the deep end;
    The pH is between 7.2 and 7.8, and;
    FC is between the minimum and shock level for your CYA level per the Chlorine / CYA Chart.
    Pool School - Chlorine / CYA Chart
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: My FC is off the chart - Help!

    Quote Originally Posted by needsajet View Post
    The pool is safe for swimming when:
    You can clearly see the bottom of the pool at the deep end;
    The pH is between 7.2 and 7.8, and;
    FC is between the minimum and shock level for your CYA level per the Chlorine / CYA Chart.
    Pool School - Chlorine / CYA Chart
    Thank you!
    20 X 40 lazy L, vinyl liner, chlorine, approximately 33,000 gallons, automatic chlorinator, DE filter, HP 1.5 variable pump, dolphin Triton cleaner
    cleaner

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    Re: My FC is off the chart - Help!

    Quote Originally Posted by keagle View Post
    My pool is 33,000 gallons, vinyl liner, 20 X 40. The water looks great but after testing the water with my taylor tester, the chlorine test was orange - off the chart. When I tested the chlorine with 087 powder, it was 25. The pool store said the FC was 10 - which makes sense (that the water looks great) since the CYA is 100. According to my testing it is 90.
    FC - off the chart
    CC - 0
    CYA - 90
    PH - 7.6
    TA - 100
    I use trichlor pucks in an auto chlorinator- which has been turned off for three days. We had 1 day of heavy rain and I added (a small amount of water), but only a slight change in chlorine. I know I have to get the CYA down to at least 50 and chlorine down to 5. This has never happened before. We have a new chlorinator and had it set too high for 1 day, but did not expect to see chlorine so very high. I can't remember seeing the test turn orange even after shocking.
    Any ideas of what could have caused this or suggestions to get the chlorine down?
    Hi, I had a customer using chlorine pucks in the chlorinator and the fc was off the charts. They didn't have to shock all summer. This one made me scratch my head but I found the problem (and it's very rare) the pucks they were using came from a bad batch causeing the chlorine levels to go to high. (Not sure what kinda mixture mistake can do that). Had them switch the pucks and everything went back to normal for them.

    So if the pucks your using are new this could be the problem.

    Just make sure you don't test the water right after shocking the pool as it will give you a high fc reading.

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    Mod Squad kimkats's Avatar
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    Re: My FC is off the chart - Help!

    If at all possible it is best to get those pucks out as they are just sitting in there making FC/CYA stew.........It might mean "using them up" as when you open the tube it could be nasty with chlorine fumes so use GREAT care. Once they are gone-used up or removed do NOT put any more in there please.

    The pucks do have a place in the pool world-weekend get aways and vacations and such. What TFP teaches is the how and why of everything that is added to the pool.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: My FC is off the chart - Help!

    Quote Originally Posted by RedBluePool View Post
    Hi, I had a customer using chlorine pucks in the chlorinator and the fc was off the charts. They didn't have to shock all summer. This one made me scratch my head but I found the problem (and it's very rare) the pucks they were using came from a bad batch causeing the chlorine levels to go to high. (Not sure what kinda mixture mistake can do that). Had them switch the pucks and everything went back to normal for them.

    So if the pucks your using are new this could be the problem


    Just make sure you don't test the water right after shocking the pool as it will give you a high fc reading.
    Interesting. The pucks are new this year. Purchased from a place we never used before. We will definitely check it out. Thanks for the info.

    - - - Updated - - -

    Thanks!
    20 X 40 lazy L, vinyl liner, chlorine, approximately 33,000 gallons, automatic chlorinator, DE filter, HP 1.5 variable pump, dolphin Triton cleaner
    cleaner

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