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Thread: Cannot hold FC!

  1. Back To Top    #1

    Join Date
    May 2011
    Location
    Castro Valley, CA
    Posts
    2

    Cannot hold FC!

    FC - 0
    CC or TC - 0.5
    pH - 7.3
    TA - 80
    CH - 260
    CYA - 100+ (per Leslie's test), 150 (with test strips)

    I've been adding 182oz of chlorine bleach (6%) and it would go to zero after a day (or sooner). I had my water tested at Leslie's a month ago and only had CYA of 5. This month it is 150. I have added 6-8 packs of their power powder (not plus) and used trichlor tablets but can that increase my CYA that much in a month??

    I have some algae on the walls but the water is clear. I was about to switch over to a salt system (Circupool RJ45) but only added the salt in the pool so far (tests reads 3500 ppm) but have yet to install the system yet. Does the high CYA have a major effect on the FC loss?
    21K Gallons
    Cartridge Filter (Pentair CC250)
    IG, Plaster
    1.5HP

  2. Back To Top    #2
    frogabog's Avatar
    Join Date
    Jul 2010
    Location
    Portland, Oregon
    Posts
    1,578

    Re: Cannot hold FC!

    Quote Originally Posted by hwwjr71
    Does the high CYA have a major effect on the FC loss?
    Major isn't the word for it. Your pool at that level will need to target around 18ppm of chlorine every day just to make it through the day w/sun and bathers. And that's only if you have no algae issues. On the best algae free day you should expect to loose 50% of your chlorine. At high CYA levels like you have (it very well could be much higher, the testing is not accurate much above 100ppm) that means you'll loose 9ppm per day... every day and will need 9-11ppm sitting in the pool at all times (inactive chlorine).

    9ppm/day is for a 1000 gallon pool is just under 1.5 gallons of 6% bleach. How many gallons is your pool? If you're at 2000 gallons that means you will need 3 gallons of bleach a day just to stay sanitary.

    The CC reading you got is not valid. Ignore it. You have visible algae, you need to shock.

    See pool school. Read it a few times, focus on the algae section. Read it again. Focus on the shocking process and read that again... again... Take to heart the concept that shocking is not a product or a one time action, but rather a process that has to be completed. You can't throw stuff in and walk away expecting miracles.

    Get a proper FAS-DPD test kit. Leslie's can't be trusted to sell you the correct one and you can't be sure you will be at shock level, or complete the shocking process without it. (you can of course luck out, but you won't know till you fail or succeed. Would you put a possibly broken part into your car... just in case it worked?) The TF100 is the best deal around and shipping is amazing fast. See http://www.tftestkits.net

    You will need liquid chlorine, either 6% regular un-cented no nothing special bleach, or you can buy 10-12% liquid from a pool store. Either works, about the same price.

    You also will need to drain and refill a total of around 70% your pool to get it to a manageable CYA level. With it that high, you'll want to drain part (30-50%).. refill... drain part (another 30'ish)... refill... test for CYA... etc. A sort of dance that will get you down to a CYA level that won't take 33ppm to shock, and 11-18ppm per day minimum maintained chlorine level.

    40-50ppm CYA is an average sunny location number to aim for, but if you're going with the SWG you can drain and dilute to 70-80ppm instead (SWG's run best on a slightly higher CYA level than liquid chlorine only pools).

    Other than a green swamp, the most common issue with those looking for a solution to their pool battle is high CYA. Tablets, dichlor shock products/chlorinating both add CYA every time you put them into the pool. CYA doesn't go away, and chlorine demand increases and increases till it's impossible to even attain the required level with the products that produced the high demand.

    Oh, almost forgot. Get friendly with the pool calculator http://www.poolcalculator.com you will be using it frequently.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

  3. Back To Top    #3
    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Cannot hold FC!

    Before continuing you really need to find out what your CYA level really is. Very low CYA and very high CYA plus algae (not always visible) will both result in losing all of your chlorine every day. It isn't at all easy for CYA to go up that much, but that doesn't tell us which of the test results are wrong.

    Power Powder is cal-hypo, which adds chlorine and calcium. Trichlor tablets contain CYA, but they add CYA very slowly. At most one month of trichlor could have raised CYA by 60, and 40 is much more common.

    The chances are that CYA is really high and you will need to replace water to get it below 100 before continuing, but that is fairly drastic and it would be good to get a more reliable test result before going to all that effort.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  4. Back To Top    #4

    Join Date
    May 2011
    Location
    Castro Valley, CA
    Posts
    2

    Re: Cannot hold FC!

    Will do. Just ordered the TF100 kit.
    21K Gallons
    Cartridge Filter (Pentair CC250)
    IG, Plaster
    1.5HP

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