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Thread: I would have to raise the FC to about 30

  1. #1
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    I would have to raise the FC to about 30

    Hi

    Newbie here Many thanks for this great forum to help me.

    I was about to shock my Salt Water Pool so thought the best place to read up on it was here but now I am more confused than ever

    My CYA is about 70-80
    My FC based on the recommendations here is being kept around 5-6FC
    My CC is about .2
    BUT My overnight FC drop is about 1.5 -2.0FC

    My pool is clear but get a lot of dead algea dust on the bottom it has also been super hot here recently

    If I use the table here on shock level based on my CYA level i would have to raise the FC to about 30FC however not one product recommends this. I even caontacted HTH and they could not understand this. According to them I should be only shocking to a level of 5FC which I already am at I was told I run the risk of damaging equipment at this level.

    I have just exhausted Google trying to get an answer

    Is this reading of 30 meant for NON salt water pools?
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  2. #2
    Administrator JasonLion's Avatar
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    Re: I would have to raise the FC to about 30

    The majority of the pool industry is in denial about what CYA does. When CYA is around 70 to 80 you need to use much higher FC levels than you would need to use when CYA is lower. However much of the pool industry simply takes the numbers that would work if CYA was zero, and repeats them regardless of the CYA level. Obviously shocking to 5 will not work. If it would work it would have already worked for you.

    There is no risk what so ever to the equipment of having FC around 30 when CYA is 70 or 80. There would be a risk if CYA was actually zero.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. #3
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    Re: I would have to raise the FC to about 30

    Welcome to the forum.
    Obviously shocking to 5 will not work. If it would work it would have already worked for you.
    +1

    Unless you bring your FC up to that 30ppm value (and HOLD IT there until you pass the OCLT), you will simply continue to stay stuck using additional chlorine to fight the algae (and subsequent "dust") you are seeing.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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    TFTestkits , PoolMath , Pool School

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    Re: I would have to raise the FC to about 30

    Quote Originally Posted by duraleigh
    Welcome to the forum.
    Obviously shocking to 5 will not work. If it would work it would have already worked for you.
    +1

    Unless you bring your FC up to that 30ppm value (and HOLD IT there until you pass the OCLT), you will simply continue to stay stuck using additional chlorine to fight the algae (and subsequent "dust") you are seeing.
    Yeah, that. Unless you want to drain your pool to get your CYA back to zero, which is NOT recommended
    IG Plaster 20,000gal, attached spa w/ spillover, hayward C12002 cart filter, 1 1/2hp pump w/ polaris 360
    6/16/12 - PH 7.6, FC 6, CC 0, CYA 30, TA 80, Calcium 310

  5. #5
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    Re: I would have to raise the FC to about 30

    Welcome to the forum Michaelandliz

    Trust what you are reading here in pool school. look what you are going through right now and then read some of the threads here. If you want a clean and trouble free pool follow the advice, it's free and it works.

    Did I mention read POOL SCHOOL?
    18' x 42" Intex (4786 Gal @ 80% capacity) Intex 8110 SWCG, 2000 GPH cartridge filter.
    Full Sun, Well Water, Borates at approx. 50
    TFTestKit-100--The Pool Calculator--Pool School

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    Re: I would have to raise the FC to about 30

    wow -ok thanks for the help, thats a heck of a lot of chlorine I need to add to 17,000gals

    My other concern is I have a 3 year old daughter that swims daily, when I have shocked before to about 12FC following the companies guidelines it takes about 3 days for the FC to drop back to about 5. I could never let our Daughter swim in 30FC and I fear the pool would be closed for weeks while i wait for it to drop back down.

    Sorry if these sounds like amateur concerns to the professionals but i am thinking of living with a bit of dust rather than filling the pool with so much chlorine. The pool is crystal clear and the CC was 0 this morning although I lost about 1.5FC overnight which of course tells me there is a bio load.

    The SWG is set to 50% and the pool pump is on for 11 hours a day. we have had scorching weather here the past 3 weeks and the pool is in constant full sun, the pool temp is averaging 86F daily.

    In a complete conundrum what is best.
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  7. #7
    Senior Member Richard320's Avatar
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    Re: I would have to raise the FC to about 30

    Quote Originally Posted by Michaelandliz
    wow -ok thanks for the help, thats a heck of a lot of chlorine I need to add to 17,000gals

    My other concern is I have a 3 year old daughter that swims daily, when I have shocked before to about 12FC following the companies guidelines it takes about 3 days for the FC to drop back to about 5. I could never let our Daughter swim in 30FC and I fear the pool would be closed for weeks while i wait for it to drop back down.

    Sorry if these sounds like amateur concerns to the professionals but i am thinking of living with a bit of dust rather than filling the pool with so much chlorine. The pool is crystal clear and the CC was 0 this morning although I lost baout 1.5FC overnight

    The SWG is set to 50% and the pool pump is on for 11 hours a day. we have had scorching weather here the past 3 weeks and the pool is in constant full sun, the pool temp is averaging 86F daily.
    That's a pretty big drop overnight.

    It's safe to swim up to shock levels. And if you shut off the SWG FC should come down really fast anyway.

    You're walking a tightrope. At least crank up the SWG or dump in some bleach to get FC to 9 or 10, same level as a non-SWG pool should have.
    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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  8. #8
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    Re: I would have to raise the FC to about 30

    I will likely follow the advise then and put in the bleach I have found the pool calculator to work out how much.

    My other concern is bleaching my lovely deep blue liner.
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  9. #9
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    Re: I would have to raise the FC to about 30

    How are you testing to have determined what your overnight loss is? It does sound like you need to follow the shock process per instructions on this site (because you mention seeing algae), but I am curious how you are testing.
    POOL: Intex ultra new in 2014 (32 x 16 x 52) (seasonal; on concrete pad covered with 1.5" extruded or whatever foam insulation sheets - ugly, but comfy); added a through-wall skimmer; I add salt for feel. EQUIPMENT: Pentair SuperFlo pump (1HP, 2SPD); Pentair cartridge filter (200 sq. ft); Pentair MasterTemp natural gas heater (400,000 btu) Climate/Location: Lincoln, Nebraska

  10. #10
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    Re: I would have to raise the FC to about 30

    I am using the taylor test kit and testing using the 25ml more accurate .2 drip rate.

    wow ok so according to the chart i need 7 gallons of bleach at 6% strength.
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  11. #11
    Senior Member techguy's Avatar
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    Re: I would have to raise the FC to about 30

    Sounds ok. If you buy 12%, you could use half as much.

    Don't forget...when the FC drops below the shock value for YOUR CYA, it's safe for DD to swim.
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

  12. #12
    Senior Member linen's Avatar
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    Re: I would have to raise the FC to about 30

    Welcome to tfp, Michaelandliz

    Quote Originally Posted by Michaelandliz
    I am using the taylor test kit and testing using the 25ml more accurate .2 drip rate.
    I would switch to the 10 ml sample and save your reagents. Each drop will then be 0.5 ppm, which is more than enough accuracy for proper chlorine maintenance. See: http://www.troublefreepool.com/exten...1.html#p206393

    Quote Originally Posted by Michaelandliz
    wow ok so according to the chart i need 7 gallons of bleach at 6% strength.
    Since we do not know the volume of your pool, we can only guess. If your pool is 20000 gallons, then to get 21 ppm (FC shock level for 80 ppm per poolcalculator.com), you would add 871 ounces (about 6.75 gallons) of 6% Bleach. Is your pool 20000 gallons?

    Please put your pool and equipment details in your signature. It help us help you.
    TFP Moderator who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  13. #13
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    Re: I would have to raise the FC to about 30

    Hiya

    thanks for your help

    my pool is approx 17,000 gallons its kidney shaped with a hump (no I dont mean its upset with me )and 36x16 and about 8' deep end and 3' shallow

    equipment
    Pool liner
    mainly haywood
    gas heater
    5 x Heliocol solar panels
    1hp super pump (to be replaced soon with something quiet!)
    sand filter
    SWG
    Pro logic controller
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  14. #14
    Senior Member elwood58's Avatar
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    Re: I would have to raise the FC to about 30

    Looks to me like you need 600 oz (just under 5 gal) of 6% bleach to get to your shock target of 21. You will need some extra on hand to keep it there, which you need to do until your pass OCLT, Water is clear and CC .5 or less.

    This is one of those cases where I would just get 12.5% Liquid Chlorine from a high volume source, as it will be a lot less to transport. I would get 4 gallons, as you have an SWG, and hope not to shock again anytime soon. 12.5% not not have as good a shelf life as 6% Bleach.
    14100 Gal IG MiniPebble, Pentair Intellichlor IC-40 SWG, Sand Filter, Pop Up Cleaning, Intelliflo VS Pump, Aquacal Heatpump/Chiller, 1/4 Acre Desert Landscaped, Lots of Deck. Built in 1984, updated in 2012 and 2014
    "If you don't measure it, you can't manage it!"

  15. #15
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    Re: I would have to raise the FC to about 30

    Hi

    thanks for your help.

    I read the CYA/FC chart and it said 30 for SWG pools, whats the reason for 21? of course I prefer this lower number

    My pool is crystal clear and my CC was 0 as of this morning even on the 25ml more sensitive test, I just get FC loss overnight on several tests. I also get the brown dust, but after vacuming twice with a electical robot vac with hyper filtration that seems to have deminished by 75%. So the main issue is FC loss.
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  16. #16
    Senior Member elwood58's Avatar
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    Re: I would have to raise the FC to about 30

    I used your 17,000 Gallons, and a CYA of 80, in the Pool Calculator.
    14100 Gal IG MiniPebble, Pentair Intellichlor IC-40 SWG, Sand Filter, Pop Up Cleaning, Intelliflo VS Pump, Aquacal Heatpump/Chiller, 1/4 Acre Desert Landscaped, Lots of Deck. Built in 1984, updated in 2012 and 2014
    "If you don't measure it, you can't manage it!"

  17. #17
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    Re: I would have to raise the FC to about 30

    I got the 30Fc from the pool school table
    pool-school/chlorine_cya_chart_shock

    So which is right?

    sorry to be a pain.
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  18. #18
    Administrator JasonLion's Avatar
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    Re: I would have to raise the FC to about 30

    They are both right. In any normal situation either number will work, though the Pool School numbers will work more quickly. The chart in Pool School is a little more conservative, i.e. reduces the odds of there being a problem.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  19. #19
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    Re: I would have to raise the FC to about 30

    Ok that makes sense to confused old me now, ok will go by 21 (yeah less chlorine to add )

    I will do another FC test overnight just to be quadruple sure I actually need to do this as my CC is 0 and do have a crystal pool, I will also not vac the pool and see what shows up.
    17,000 gal SWG pool
    Liner, 5 x Heliocol solar panels, Haywood gas heater, Super Pump II 1HP, Haywood pro sand filter, Haywood T cell-15, Pro Logic controller,
    Taylor test kit controlled pool
    Params - 5.0FC (if not shocking) ca-270, ALk-100, pH-7.2-7.6, NACL - 3000, CYA -60-70

  20. #20
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    Re: I would have to raise the FC to about 30

    Quote Originally Posted by Michaelandliz
    wow -ok thanks for the help, thats a heck of a lot of chlorine I need to add to 17,000gals
    Now you know why I have done everything possible to make sure I never have to shock again. Imagine how much it took me to shock my pool for two weeks!
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II T100 Sand Filter, CompuPool CPCS48 SWG, TF-100 test kit

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