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Thread: Low FC

  1. Back To Top    #1

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    Low FC

    Greetings,

    I am in the process of following the recomended water balancing technique as taught in this great forum. My 2 months old pool were filled with pipe water with presumeably no or low CH and CYA. My existing 4 in 1 test kit can only test:
    FC 0.2
    ph 7.8
    TA 50
    Acid Demand 0
    Dave had shipped my TF100 and hopefully getting it next week before testing further. I've switched my SWG off and throw in 2 pcs of Trichlor tablet to get the chlorine and CYA as I cannot get CYA on it's own. However, my FC is still very low at 0.6 right after pump circulation and drop to 0.2 or 0 at the end of the day without any sun (rainy or cloudy day) and no bather. The water temp is 27 C or 80 F. The water are still clear so why is the FC not increasing. I'm thinking of throwing in some liquid chlorine (Sodium Hypochlorite 10%) to bring the FC up and leave overnight to see if it works ( correct me if I'm wrong)and by how much? Once I got the TF100, I can check the CH and if low, can get Cal Hypo here to build it up but I cannot get Borax around. Can anybody advice on where I can get borax in other form and the consequent of not having Borates? Once my basic chemistry are in order, I'll switch back to SWG.
    Thanks guys and ladies for your time.
    Vincent.
    8,000 gal IG concrete & tiled lap pool, 1/2 hp pump, 24" sand filter, SWG Auto Clean, whole pool under shed, 3 X 2ft waterfall one end overflow the other end. TF100 Testkit. 80 F Water whole year round.

  2. Back To Top    #2
    JasonLion's Avatar
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    With either no CYA or very low levels of CYA you will lose FC to sunlight very quickly even on a cloudy day. The nice thing about very low CYA levels is that you don't need very much FC to keep the pool safe.

    If you continue with the trichlor two at a time until you have used a total of 5 to 6 lbs of trichlor you should end up with a reasonable CYA level. Then you can either turn on the SWG or switch to liquid chlorine.
    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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    duraleigh's Avatar
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    Hi, Vincent,

    Your FC is a consumable item and something you will need to replenish constantly. Even with CYA to protect it (somewhat) from the sun, it will still be consumed. Clouds do not stop the sun from reducing your FC. No swimmers in the pool is helpful but FC will still be consumed. FC kills organics that enter your pool....leaves, suntan lotion. germs, algae, etc. In so doing it is depleted. It is also depleted from the sun's UV rays...cloudy or not. You can diminish the loss of FC to the sun with CYA (Cyanuric Acid) I believe you can find CYA somewhere over there if you keep looking. Once you get that in there in the 60ppm or so range, your FC loss will be greatly reduced.

    If you truly cannot find CYA anywhere, I would suggest (like you are already doing) you consider shutting of your SWG for the Summer and chlorinating with pucks until your CYA get to 60-80ppm....it may take more than one summer to do that with pucks alone.

    If it turns out your CH is low as well, Cal hypo will take a VERY long time to get that up to speed....let's wait 'til you test your CH and go from there.

    Right now, getting CYA in your pool is far more important.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4

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    Thanks guys for the speedy replies.

    Would the 2 pucks (continuously replaced) be sufficient to keep algae at bay even with 0.2-0.6 FC? If not sufficient, I'll need more CL right? Considering the expected duration for me to run on pucks only for me to build up my CYA, is it safe for the SWG cell? I'm running the controller (to keep timer and other safety feature such as run dry protection etc) at 0% output. Ofcourse I still need to confirm CH.

    Thnaks again guys....

    Vincent.
    8,000 gal IG concrete & tiled lap pool, 1/2 hp pump, 24" sand filter, SWG Auto Clean, whole pool under shed, 3 X 2ft waterfall one end overflow the other end. TF100 Testkit. 80 F Water whole year round.

  5. Back To Top    #5
    JasonLion's Avatar
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    Yes, it is safe to turn on the SWG as long as the salt level is appropriate. However, I am not sure how you can figure out the appropriate percentage to set it to before the CYA level is right. The key thing is that as the CYA level goes up the percentage you should set the SWG to goes down and if you fail to keep an eye on it the FC level could get way too high, which would be bad.

    While the CYA level is very low a good sunny day could wipe out almost any amount of chlorine you put into the pool. There is no way you are going to be able to maintain FC in the afternoon while CYA is low. Once the CYA level comes up two trichlor tablets are going to be plenty, perhaps even more than enough. I think you will be fine with just the trichlor tablets.
    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

  6. Back To Top    #6

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    Thanks Jason,
    I will stick to the pucks only for the time being until I get my TF100.

    Cheers.

    Vincent.
    8,000 gal IG concrete & tiled lap pool, 1/2 hp pump, 24" sand filter, SWG Auto Clean, whole pool under shed, 3 X 2ft waterfall one end overflow the other end. TF100 Testkit. 80 F Water whole year round.

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