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Thread: How much will this raise my FC level?

  1. Back To Top    #1

    Join Date
    May 2007
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    Haughton, La
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    How much will this raise my FC level?

    Pool is 27ft round, 4ft deep.

    How much will a 1 pound bad of shock raise my FC level? Bag is marked 73% Cal Hypo
    27ft Above Ground Pool
    Sand filter

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    I get 17000 gallons and a 5 ppm increase in FC for 1 lb of 73% calhypo.

    You can use my pool calculator, see the link in my signature to answer questions like this one, though it does take a little more work to go backwards. My pool calculator is designed to go from the desired increase in FC to the amount of calhypo, but by trying a few numbers till you get the weight you want it is possible to go backwards.
    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

  3. Back To Top    #3

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    May 2007
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    Thanks...I just wanted to make sure I was getting up to shock level. My water has the green tint to it.

    Cya is 50-ish, FC was at 9.5 with 0 CC, I added to bags so that should be about right.
    27ft Above Ground Pool
    Sand filter

  4. Back To Top    #4

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    Mar 2007
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    San Rafael, CA USA
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    bassadict69, did your FC level drop to a low level when the green occurred or are you saying that at a minimum FC of 9.5 and a CYA of 50 ppm you are now seeing green? Did the water get dull and then hazy and then cloudy before it turned green? Did the pH go up before the pool turned green or did you add chlorine before it turned green (could be copper instead of algae)?

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  5. Back To Top    #5

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    May 2007
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    Haughton, La
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    I make dang sure not to add anything with metals & got it tested about a week ago & metals came back zero.

    FC has not been allowed to drop below 8, I can shock it to 20 for a few days & the best it will do is lighten up a little but keeps the green tint & it settles on the bottom until we stir it up...then it is green again. pH has been holding steady at about 7.4 all season. No problems there.

    Phosphates are off the chart due to bad community water. We struggle with this every year until we do a Phos floc, then we are good til the end of the season. We just started the floc tonight & started another thread following the progress.
    27ft Above Ground Pool
    Sand filter

  6. Back To Top    #6

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    If you know what the phosphates level is, let us know -- even if it's "at least" some large number. It would be good to know when the disinfecting chlorine level isn't enough to keep away green algae at the normally recommended levels. Though this is one data point, it's a start to figuring out when a phosphate remover makes the most sense.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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