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Thread: Latest numbers and FC question

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    esim13's Avatar
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    Latest numbers and FC question

    After a brief 3 person swim, I ran my numbers and here's what I got:
    FC 2.5
    CC 0
    pH 7.6
    TA 100
    CH 150

    I test FC and pH daily. My FC usually drops 3-4ppm a day. I try to keep my target at 7 (CYA tested 60 a few weeks ago.) So I'm adding roughly 2 quarts a day. My pool is in full sun but I thought I wouldn't be adding so much daily. 8 cups a day just seems like a lot to me. Is this pretty normal?

    Also, how often do I need to test CYA? I'm asking because of the amount of water evaporation and new water added every few days (and we haven't even hit the high temps yet My water temp is 81 right now and the sun hasn't been out for 2 days.

    Thanks!
    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

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    Re: Latest numbers and FC question

    3-4 ppm is more than the average loss reported here of about 2ppm (generally....each pool is different). YOur CYA will stay constant (generally, again) over the course of the summer. You'll loose some from splashout and may need to replenish 10ppm or a little more in a season.

    What is your last CYA reading?

    How does your water look?

    Those answers may give us a clue as to your chlorine loss.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    esim13's Avatar
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    Re: Latest numbers and FC question

    Water is clear, sparkly and overall great. We did have some days of straight sun but not sure if that played a roll in this. Here's my FC readings from last week..
    M 2
    T 3
    W 3
    Th 3
    couldn't test Friday (rain)
    today 2.5 I added 1-96oz. jug of bleach and will retest after this post.

    On 4/17 I tested CYA and it was (what I believed to be) 60. I tested it again on 4/23 and I believe it was more accurate at 40. However I wasn't sure so I've been keeping my target FC at 7 still. Would I be safe keeping target at 6 or should I retest CYA again?
    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

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    esim13's Avatar
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    Re: Latest numbers and FC question

    I just retested and my numbers are:
    FC 8
    CC .5

    I also just took some pictures. Don't have a pool light, flash used, spotlight on corner of house.



    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

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    Re: Latest numbers and FC question

    Your water looks great! Nice work. I was concerned that your FC was dropping too low for your CYA level (it may be, but not enough to matter, IMO)

    That could have caused your water to develop a little bit of a dull look which is the first signs of algae growth which, in turn, would account for your FC loss being a little high. None of that seems to be the case.

    I wouldn't panic about a 3-4ppm loss during the day but I would continue to test it from time to time. It's at the higher end of normal.

    Do a daytime loss test by testing before the sun hits the pool and then again just after the sun is off the pool and don't add any chlorine in between. Do it with the FAS/DPD test for accuracy. Let us know that result.

    I would say your CYA is fine. If it looked like 60 once and now looks like 40 you are in the right range. the vagaries of that test make it hard to get much closer than that at least the first few times you try it. Perhaps test it in a week or so just to compare. You can also empty the solution out of the view tube and do it several times over to help you get a feel for the test.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Richard320's Avatar
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    Re: Latest numbers and FC question

    Just a thought...

    Are you testing the actual FC morning and evening? Or are you testing, calculating, and adding? Could you have some weak Chlorine, so you're adding what should be 4ppm, but it might really be much less?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    esim13's Avatar
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    Re: Latest numbers and FC question

    I usually test around 6 in the evening. Calc on iphone and add what's needed. Chlorox from Wally World.. - don't know about weakness but I'll keep it in mind.

    Now, I just got confused when duraleigh said test with the FAS/DPD test. I use the Taylor K-2006 testkit. I follow the directions on the cover daily for FC, and CC then test pH. Is this FC, CC part the FAS/DPD test? Is there some other daily FC test?
    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

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    frustratedpoolmom's Avatar
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    Re: Latest numbers and FC question

    If you are sure you have the K-2006 and not the K-2005, then yes, you are testing with the FAS-DPD test. There is an OTO yellow chlorine test that tests for TC and is not as accurate or useful.

    Tomorrow morning before the sun hits the pool test the FC again - if you lose more than 1ppm something organic is consuming the chlorine too.

    We recommend testing in the evening after the sun is off the pool - to take the sunlight out of the equasion.
    If you are only testing at 6pm, and then adding bleach, but not testing again- you can't confirm if you've actually reached your target or not, KWIM? You may think you are reaching 7 but only hitting 5 and then you've only lost 2-3 in a given day, etc.

    If you test in the morning and it's a 7 or 8 and then in the evening tomorrow test again you should have a better idea of what's happening. Just make sure to test before the sun hits the pool. No sleeping in, LOL
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Latest numbers and FC question

    Quote Originally Posted by esim13
    Is there some other daily FC test?
    There are 3 different chlorine tests that are worth anything.
    - FAS-DPD uses a powder to turn the sample pink, then you use drops to make the pink go away.
    - DPD uses drops to turn the sample pink and you compare it to a color block.
    - OTO uses drops to turn the sample yellow and you compare it to a color block.
    FAS-DPD tests FC and CC. DPD tests FC and TC; OTO does only TC. (TC = FC + CC) FAS-DPD is included in the K-2006, DPD is in the K-2005. People trying to buy K-2006 sometimes get K-2005 instead; that's why we double-check.

    The CYA test, as you know, is a bit tricky. You get the best results if you do it in daylight with your back to the sun, or with equivalent bright indirect light. Also you can do the black-dot-disappearing part several times, to see if you get the same answer each time (I usually run it 3 times).
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    esim13's Avatar
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    Re: Latest numbers and FC question

    I tested a 6:30 this morning with a FC 6.5. I lost 1.5 FC overnight. My CC is back to zero. It has been overcast and rainy all weekend but I will still check FC after the sun really goes down tonight and post back.

    Thanks everyone!
    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

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    esim13's Avatar
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    Re: Latest numbers and FC question

    Just did FAS/DPD daily test and got 3.5 for FC. CC's still at 0. I'm surprised my daily use is still 3ppms today with no sun! It has been raining off and on all day, very overcast. It's supposed to continue raining slightly til Tuesday. Gloomy and sticky - gotta love S. Louisiana weather!

    To sum it up I lost 1.5ppm overnight and another 3ppm today. Should I be worried?
    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

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    Re: Latest numbers and FC question

    Should I be worried?
    No, because you can fix your issues.

    You either have some testing error in there or you still have some organics in your pool. Recheck how you did the test and if you're comfotable with your results, you need to elevate your FC and keep it there until you can pass that overnite FC loss test of 1.0 or less.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    frustratedpoolmom's Avatar
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    Re: Latest numbers and FC question

    Yes. You need to shock. If you lose more than 1ppm you have organics consuming the chlorine a "nascent algae" situation - you are staying just one step ahead of it.... it explains why the daytime loss is higher than normal.

    Shocking should take care of it - just raise it up and hold it there until the FC holds overnight or you lose less than 1ppm.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Latest numbers and FC question

    Should I be worried?
    Quote Originally Posted by duraleigh
    No, because you can fix your issues.
    Quote Originally Posted by frustratedpoolmom
    Yes. You need to shock.


    No, you shouldn't be worried, but yes you do need to do something about it.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    frustratedpoolmom's Avatar
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    Re: Latest numbers and FC question

    Exactly. Well said, Paul!
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  16. Back To Top    #16
    esim13's Avatar
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    Re: Latest numbers and FC question

    So I came home today, tested and FC was 4.5. I retested CYA and got 60. I knew I needed to shock so I looked on my iphone app and it said I needed to shock at 18 for a CYA of 60. I looked on Pool School just to make sure and it says shock is at 24 for a CYA of 60. Which one do I go by?
    10,408 gallon, 21' round, 52 in' deep AG, half in ground
    Artesian Clear Master Plus Sand Filter, Artesian Turbo King 2 hp pump, installed June 08
    Denham Springs, Louisiana
    GEAUX TIGERS!
    Pics taken 2012
    http://i941.photobucket.com/albums/ad25 ... CN0606.jpg
    http://i941.photobucket.com/albums/ad25 ... CN0607.jpg

  17. Back To Top    #17
    frustratedpoolmom's Avatar
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    Re: Latest numbers and FC question

    18 is fine, the 24 would likely work faster.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Latest numbers and FC question

    The shock levels are as much art as science; Pool School and the Pool Calculator had different artists.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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