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Thread: Overnight FC Not Holding and Other Questions

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    Overnight FC Not Holding and Other Questions

    I'll give you a little background first. I got a new liner last year, and after that, I could not get my pool clear. I was not following the BBB method carefully, but I was using bleach. Anyway, same thing at the beginning of this year, water not clear. Also, I would get big foamy green clumps of algae and some very green water. I had that last year and the beginning of this year. I would shock my pool, but I never held the level up, and I just didn't get things under control. Imagine that! Anyway, so this year, I'm doing my best to get my numbers in line. My pool gets full sun most of the day.

    A few days ago, I was having some signs of algae starting up on the liner, and I had some CC, don't remember how much. I read and read, and after a while everything runs together. Here are my latest readings from about an hour ago:


    FC 14.5 (I've been shooting for a shock level of 18)
    CC 0
    pH has been 7.4, I haven't checked it in a few days because the chlorine level has been up
    CYA 45
    TA 80

    Tuesday night when I last checked it, the FC was 18.5. The next morning it was 14.5 at 10:00, 11.5 at 11:30, 13.5 at 2:00, 10.5 at 5:30, 14 at 7:00 and 17.5 at 8:30 PM. Tuesday was a sunny day. Each time I checked it, I added the appropriate amount of bleach according to the pool calculator, and I've been brushing. Even before I started this, the water was crystal clear. Wednesday's figures: 15.5 at 7:30 am, 16 at 10:30 am, 14 at noon, 10.5 at 5 pm, 15.5 - didn't write time, 18 at 11:30 pm. We had a storm yesterday, but water remained clear. Today: 14.5 at 7:30 am, 14.5 at 9:30 am. I'm not showing any CC, and I'm brushing each day. Water is as clear as can be. I have gone through many, many bottles of bleach. We haven't been able to swim all week because the levels are so high. Also, and this sounds lame. This is my first week of being on summer vacation. I like to get up at 10, and I've been having to get up to go check the levels at 7:30 each morning. I know. Whaa Whaa. I need help. I know the answer is right in front of me, but I can't see it. What is the longest some of you have done this procedure before the FC held?
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    frustratedpoolmom's Avatar
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    Re: Overnight FC Not Holding and Other Questions

    It can take a week, or more...too many variables and every pool is unique.

    So you see no more algae, the FC just isn't holding overnight? Keep at it, and have some pop, sounds like you've only been shocking since Tuesday? Sounds to me like you are doing everything right, just need a little pool owner patience. Sorry, not the answer you were looking for I know.

    You are running the pump 24/7, right? Have you backwashed (if sand) or cleaned the filter?

    As for swimming, if you stick to shocking at night, it's okay to use the pool during the day - many members report swimming at FC levels that are elevated-but-under- shock level with no ill effects. For example if you wanted to swim and your FC was 10 I'd say go for it.
    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: Overnight FC Not Holding and Other Questions

    I have been running the pump 24/7. I did backwash once. It really didn't look like it needed it. Should I have? I've been adding bleach each time I check it to get it to 18, even during the day. Is that correct? Should I do it more frequently, like every hour during the day? BTW, thanks for the quick reply. I am correct in thinking that I need to try to hold it at 18 day and night until it doesn't drop overnight, right? I think I read that it shouldn't drop more than 1 ppm overnight.
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    Re: Overnight FC Not Holding and Other Questions

    You should be backwashing whenever the pressure rises 8psi over clean-filter pressure. Has your pressure been rising?

    Checking/adding FC as frequently as you can will probably make the shocking go quicker, but a couple times a day is usually good enough after you get going.

    You're right: You want the FC to drop by 1ppm or less overnight, it won't necessarily retain 100% FC overnight.

    For me, vacuuming helped the pool clear up and FC hold. It will get the dead algae and any other junk off the bottom.
    IG ~15,000 Gallon Plaster Pool with Attached Spa
    Hayward SwimClear C4025 - 150GPM, Cartridge
    2hp Pump 1.1 Service Rating
    Direct sunlight most of the day

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    Re: Overnight FC Not Holding and Other Questions

    Pressure has not been rising. Hmm I have not vacuumed. I guess I'll go out and do that now. I know it's only been a couple of days, but it seems like forever with all the checking and all the bleach I've gone through.
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    Guest

    Re: Overnight FC Not Holding and Other Questions

    You need to add chlorine more than just once a day. If you can add it three or 4 times a day it would be better! Hourly even better yet!

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    Re: Overnight FC Not Holding and Other Questions

    I am adding it after I check it. As you see above, that is several times a day. Yesterday it was 6 times.
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    Guest

    Re: Overnight FC Not Holding and Other Questions

    I would shoot for a higher FC level. I would go for about 25 ppm. It is not high enough to cause bleaching of the liner and you should be able to complete the process much faster. The trick is to try and maintain the FC at as constant a level as possible. Once you get it under control I would suggest adding borates to your water since you seem to have a predisposition to algae. Also, since the pool gets a lot of sun you might want to consider raising the CYA a bit (perhaps to 60 ppm) and running your FC at 6 to 8 ppm and shocking (when needed) to 25-30 ppm.

    I am not totally convinced that your FC loss is caused by algae and suspect that your CYA test results might be off. The CYA might be a bit lower than you think and the chlorine is burning off in sunlight. The only way you can tell is to put chlorine in after dark and test it right before sunrise. If you have chlorine loss then you have something growing. I suspect you will not see chlorine loss, however. I would really like to see you test this before proceding further. IF the results are what I think they are going to be you will only have to wake up early one day!

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    Re: Overnight FC Not Holding and Other Questions

    I do think that my CYA needs to be higher, but I was told to start low and take it from there. I have been testing and adding chlorine after the sun goes down and testing in the morning before the sun hits the pool. I'm losing a good bit at night. I just vacuumed it. Should I continue with this process and address CYA later or should I re-check CYA and add more stabilizer before I continue with the shocking?
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

  10. Back To Top    #10
    Guest

    Re: Overnight FC Not Holding and Other Questions

    Quote Originally Posted by Sallie
    I do think that my CYA needs to be higher, but I was told to start low and take it from there. I have been testing and adding chlorine after the sun goes down and testing in the morning before the sun hits the pool. I'm losing a good bit at night. I just vacuumed it. Should I continue with this process and address CYA later or should I re-check CYA and add more stabilizer before I continue with the shocking?
    IMHO, you should shock to a higher FC level like I suggested. Once your FC is holding overnight then raise the CYA a bit.

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    Re: Overnight FC Not Holding and Other Questions

    Got a question. When I do the FC test, do I use a heaping scoop of powder or do I level it off? I've been doing it one way, but something I read makes me think that I may be doing it wrong.

    I'm still going, and it will be a week tomorrow. I bet I've spent $200 on bleach since I started this. It is getting old!
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    frustratedpoolmom's Avatar
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    Re: Overnight FC Not Holding and Other Questions

    Heaping scoop.
    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: Overnight FC Not Holding and Other Questions

    Or two level scoops; should work out the same, I find it easier to do level scoops.
    --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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    Re: Overnight FC Not Holding and Other Questions

    So you do 2 level scoops even if the first scoop makes the water turn pink?
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    reebok's Avatar
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    Re: Overnight FC Not Holding and Other Questions

    the directions for the TFT test kit is one heaping scoop. the directions (from what I gather) for the taylor k-2006 test kit is two (level) scoops. pick whatever way you want, but make sure you do one of those ways. too little can be an issue, too much is not an issue.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: Overnight FC Not Holding and Other Questions

    I'm using one of Ben's 232 test kits with new reagents from Taylor, seems like a level scoop versus a heaping scoop allows a lot of room for error.

    Back to my problem of not holding FC overnight, it's been a week today. I can understand if I started with a green pool, but mine was sparkling clear. I've been brushing, vacuuming, checking, adding bleach. I am so sick of it. I don't think it's ever going to happen. I have been shocked at the number of bottles of bleach I have gone through. And we're not able to swim. A week doesn't seem like a long time, but the weather has been beautiful for swimming. I am just so frustrated. I know that my CYA is low for my situation (full sun). Do you think I should re-check that and get some stabilizer in there, or must I wait until this FC thing is over? I was within 2 ppm this morning, but one other time I was close and then it got farther apart, so I'm not hopeful.
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

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    Re: Overnight FC Not Holding and Other Questions

    Quote Originally Posted by Sallie
    seems like a level scoop versus a heaping scoop allows a lot of room for error.
    TWO level scoops. I do it that way 'cause I think I was way overdoing the heapiness.
    --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: Overnight FC Not Holding and Other Questions

    Quote Originally Posted by Sallie
    I'm using one of Ben's 232 test kits with new reagents from Taylor, seems like a level scoop versus a heaping scoop allows a lot of room for error.

    Back to my problem of not holding FC overnight, it's been a week today. I can understand if I started with a green pool, but mine was sparkling clear. I've been brushing, vacuuming, checking, adding bleach. I am so sick of it. I don't think it's ever going to happen. I have been shocked at the number of bottles of bleach I have gone through. And we're not able to swim. A week doesn't seem like a long time, but the weather has been beautiful for swimming. I am just so frustrated. I know that my CYA is low for my situation (full sun). Do you think I should re-check that and get some stabilizer in there, or must I wait until this FC thing is over? I was within 2 ppm this morning, but one other time I was close and then it got farther apart, so I'm not hopeful.
    No green water, crystal clear. No CC, right? Just an overnight loss? If it were my pool, I would go ahead and swim, even at the elevated levels (but below shock) during the day, and shock at night after the sun is off the pool. If there is no visible algae and no CC to irritate, no reason not to swim IMHO.

    When doing the overnight test, make sure you are testing the FC at least 30 minutes after your last bleach addition, and again before the sun hits the pool.

    A week of beautiful weather is along time to go with out swimming, I can empathize with you!

    As for the CYA, that would not account for the overnight loss. Obviously you want to verify the number for daytime purposes, but you need to get a handle on the overnight loss.

    Did you try Evan's suggestion and shock up to 25? I'd give it a try, can't hurt at this point, since you've been doing everything else right. Do it at night though, don't waste your chlorine during the day.
    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

  19. Back To Top    #19

    Re: Overnight FC Not Holding and Other Questions

    Yes, been doing FC tests exactly as described above, no CC, crystal clear. And I have been shocking to 25. We did swim one day because it went down to 9.5. I don't go under water so it didn't bother me, but my daughter came over and took one whif of me and said that the chlorine smell was very strong on my skin.

    I just thought if I added the stabilizer now that it would help keep the levels up during the day.
    Sallie
    25 K gal., vinyl IG, Hayward 3/4 hp pump, Hayward Pro Series S-220T 18" sand filter, full sun all day, no main drain - Columbia, SC

  20. Back To Top    #20
    JasonLion's Avatar
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    Re: Overnight FC Not Holding and Other Questions

    Your CYA level is already at 45, which is a good level for shocking.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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