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Thread: New Liner, New Water, No FC.

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    New Liner, New Water, No FC.

    I think I'm well on the right track (finally) but would like someone to sanity-check me.

    18x36 vinyl pool, SWCG, Sand Filter, avg depth 5.5 ft.

    We had a new liner installed (Yippee!) and filled her up with water. Followed the pool stores recommendations and took them a sample after a few days. Everything was in the ideal range, except FC=0 and CYA=0. Tested for phosphates and it was over 4000. I was told that "phosphates mask the chlorine" and if I got rid of the phosphates, the chlorine would show up. Was also told that the county sometimes buys water from Atlanta and they put phosphoric acid in the water to help maintain the pipes (?), which is probably how the phosphates got in there.

    I'm clueless and don't know any better at this point, so I buy the phosphate remover stuff and follow directions. The next day (after backwashing out all the phosphate stuff), I take another sample in and still: FC=0 and CYA=0.

    Then I'm told to set the SWCG to 100%, keep the pump running and bring a sample for testing the next day. Did that, FC still 0, CYA still 0. After that, I went to the dollar store and bought plain-jane bleach (6%) and added 10 bottles to my 26700gal +/- pool. FC was quickly high off the chart per my little test-strips. However, FC was almost back to 0 within 24hrs. Barely registered on my test strips. This was all last month and I've been knee-jerking ever since through last week. No other chems, just adding bleach hoping each time it would stick around.

    Over the weekend, like a light-bulb going off, I recalled this web site (TFP) and I started searching & reading. After a bunch of reading & *trying* to assimilate all the info, a bunch of kicking myself in the rear, here's what I've done:

    1. Ordered the TFT100 test kit. Hope it arrives this week.
    2. Determined that my problem is most likely complete lack of CYA to hold the chlorine in.
    3. Consulted the Pool Calculator which told me I need 12 lbs of CYA to go from 0 to 70.
    (Calc'd this on a smaller 16x32 pool accidentally cuz' I'm an idiot/didn't pay attn)
    4. Tied a pole to a deck table and suspended pantyhose full of CYA in front of a return jet.

    About four hours later, about 1/3 of the CYA has dissolved out of the pantyhose. The test-strip shows bloody everything in the "Ideal" range:

    TH = 250 (identical color-chart match)
    TC = 3 (identical color-chart match)
    FC = 3 (identical color-chart match)
    PH = more than 7.2 and less than 7.8 (in-between color match)
    TA = more than 80; less than 120 (in-between color match)
    CYA = 30-50 (identical color-chart match)

    SWCG is set on 80% and I'll back it down tomorrow if the chlorine gets any higher.

    Here's my immediate concern: Before I added CYA, the water tested zero for CYA on both my test-strips and the pool-store's chemical tests, so I tend to believe that was accurate. Plus it was brand new water. The Pool-Calculator advised (calculated for a 21100 gal pool to go from CYA=0 to CYA=70) it would take 12 lbs of CYA to do the trick. But, right now, with only a 1/3rd of the CYA dissolved, everything is looking pretty good. I'm nervous that the CYA will be way too high if I leave it in there overnight. I'm thinking of taking the remaining CYA out, putting it in a bucket of water and let the pump keep running overnight. I'll check the balance tomorrow and if it's still good, quit messing with it. But, if tomorrow the CYA dropped, I'll put the remainder back in front of the return jet and test it occasionally.

    Am I just being a nervous nellie -or- should I yank the remaining CYA out?
    Also, I know where CYA comes from, but what (if anything) depletes it?

    Thanks folks!
    JD Hood
    18'x36' IG Vinyl, SWCG, Sand Filter, stupid crepe-myrtles right next to the pool...

  2. Back To Top    #2
    JasonLion's Avatar
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    Re: New Liner, New Water, No FC.

    Test strips are very imprecise, especially when measuring CYA. Let the rest of the CYA dissolve and you will end up closer to the correct level than you will ever be able to guess at reading the test strips.

    CYA goes down when you lose water, either through splash out, backwashing, overflow, or water replacement. It also sometimes goes away over the winter, though that is unpredictable.
    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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    Mod Squad Bama Rambler's Avatar
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    Re: New Liner, New Water, No FC.

    New water won't have any CYA. Powdered shock and tablets add CYA so if you haven't added either of those you haven't added any CYA that way. I get 12 lbs of stabilizer to get you to 72 ppm. So if that's all you added then leave it inh there.

    Water replacement or R/O treatment is the only thing that lowers it with any certainty.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: New Liner, New Water, No FC.

    I do appreciate the quick replies!

    The test strips were an impulse buy. I thought they would be "close enough", but after reading through the forums, it appears they are akin to using the braille method to determine exact values. Fedex says I should have the TFT100 test kit sometime on Wed, so I've got that to look forward to.

    I was reading that it can take upwards of a week for the CYA to fully dissolve, disperse throughout the pool and settle into a confident reading. I guess I was thrown off a bit by the speed with which the stuff I got is dissolving. Though, I can imagine that just because I can't see the granules, doesn't necessarily mean it's yet completely dissolved? I guess?

    I'll leave it as is, let the rest dissolve and try to sit on my hands until the test kit arrives.

    Thanks again!
    JD
    18'x36' IG Vinyl, SWCG, Sand Filter, stupid crepe-myrtles right next to the pool...

  5. Back To Top    #5

    Re: New Liner, New Water, No FC.

    i dont know about phosphates "masking " the FC but i have a swg and could not keep FC in the pool... bought some phosphate stuff, got phosphates down to 300 from 5000 and no problem after that
    17,000 gal inground
    vinyl
    swg
    3hp 8 returns
    heat siphon heat pump

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    In the Industry

    duraleigh's Avatar
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    Re: New Liner, New Water, No FC.

    Jaydee,

    Waiting on the test kit is a good plan. It will give you confidence in your own numbers. (ALWAYS do your own testing).

    Tell us how your water looks.

    CYA dosage is a little confusing but you can ASSUME it's in there 24 hours after you put it in even though it may take longer than that to show on the test.

    Run like the wind from that pool store. Phosphates are essentially irrelevant in a well managed pool and they have absolutely no masking effect on chlorine. Their info is half baked to say the least.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: New Liner, New Water, No FC.

    That particular pool store is what the previous home-owners used and we've just continued doing business with them. Up until the "phosphate-phiasco", I've had no problems with them and they've always had great service and prices. Nice guys otherwise. Shame I can't trust their advice on balancing the pool anymore.

    Got the test kit. It's intimidating when you first open it, but easy enough once you start using it. Advice from one anxious noob to any others facing that kit for the first time: Read *all* the instructions, *all* the way through before you do anything! Or you'll likely dump the chlorine test too soon and have to start over to check CC.

    My numbers:
    FC = 10
    CC = 0
    PH = 7.5ish
    TA = 90
    CH = 160
    CYA = 40
    Temp = 81
    Salt = 3100 (from the SWCG controller)

    All the granulated CYA is gone into the pool; the pantyhose-in-front-of-return-jet trick got rid of it in less than two days! I'm expecting the CYA to continue to rise over the next few days as it completes assimilating. I may have to add a bit more as I calc'd it for a smaller volume pool by accident.

    I also wouldn't be surprised if the PH drops due to the CYA (if I read that possibility right) but if it does, I'll address it as needed (BBB method).

    I believe the FC is high due to keeping the SWCG on 80% or higher, and running the pump 24/7. I'm taking the pump back to a 10 hr daily runtime and dropping the SWCG down to 10% until I see the FC drop to 3. Then I'll adjust the SWCG to try and maintain FC at 3.

    All in all, I think I've got a good handle on it and you fine folks make it seem a lot easier than I was worrying it would be.

    Many, many thanks!!
    -JD
    18'x36' IG Vinyl, SWCG, Sand Filter, stupid crepe-myrtles right next to the pool...

  8. Back To Top    #8
    JasonLion's Avatar
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    Re: New Liner, New Water, No FC.

    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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