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Thread: If i let my FC dropped to zero

  1. Back To Top    #1

    Re: It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia

    hi, i am new to this forum and i have a pool for a second season.

    The pool in my new house ( bought used ) was operating for 4 to five years.
    The CYA was way high so i did a water change. Now i have stains

    Anyway, my question is:

    If i let my FC dropped to zero and i added 20 to 40 litters of water from my Aquarium where there is ammonia in it, or just pee every day in the pool without anyone seen me ( doesn't pee has ammonia ), will then the CYA will drop?

    If that's the case, then we i do not need to change my water ever again.

    Maybe all i am saying is wrong, but it crossed my mind.

    Thanks
    31,000 liters concrete vinyl pool - 1hp pump - Monarch 85kg sand filter - 2 skimmers, 1 main drain, 2 jets - safety fence - 12V leds lights par56 .[/i]

  2. Back To Top    #2

    If i let my FC dropped to zero

    Hi, i have read this forum post
    it-can-happen-to-anyone-zero-chlorine-cya-ammonia-t10974.html
    and i posted the same here for your opinions.

    "hi, i am new to this forum and i have a pool for a second season.

    The pool in my new house ( bought used ) was operating for 4 to five years.
    The CYA was way high so i did a water change. Now i have stains

    Anyway, my question is:

    If i let my FC dropped to zero and i added 20 to 40 litters of water from my Aquarium where there is ammonia in it, or just pee every day in the pool without anyone seen me ( doesn't pee has ammonia ), will then the CYA will drop?

    If that's the case, then we i do not need to change my water ever again.

    Maybe all i am saying is wrong, but it crossed my mind."

    Thanks
    31,000 liters concrete vinyl pool - 1hp pump - Monarch 85kg sand filter - 2 skimmers, 1 main drain, 2 jets - safety fence - 12V leds lights par56 .[/i]

  3. Back To Top    #3
    Ohm_Boy's Avatar
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    Re: It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia

    Maybe that's the problem... we tend to advocate NOT peeing in the pool. Could we have been wrong about that lo these many years?
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

  4. Back To Top    #4

    Join Date
    Mar 2007
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    San Rafael, CA USA
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    Re: It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia

    The ammonia is the result of the breakdown of CYA; it does not contribute in any way to CYA getting broken down. It is soil bacteria that break down CYA into ammonia. So your idea would really be to let the FC get to zero and to add soil bacteria to the pool along with nutrients (such as phosphates) to help them grow. That could also lead to algae growth as well.

    The problem with this approach is that it does not guarantee that the CYA will get converted. The bacteria may use nitrates in the pool instead or if nitrogen-fixing they may use nitrogen gas. Or the bacteria may not grow due to other limitations of trace minerals or competition from other organisms that don't use CYA as a food source, such as algae. It's not a sure-fire approach.

    Also, even if you were able to coax the bacteria to break down the CYA, you would end up with a lot of ammonia you need to get rid of. For every 10 ppm CYA broken down by the bacteria, it produces 3 ppm ammonia and that requires at least 23 ppm FC to get rid of. So the amount of chlorine needed to get rid of the ammonia resulting from a lot of broken down CYA is huge. Lowering the CYA by 50 ppm would require over 114 ppm FC cumulatively added to get rid of the resulting ammonia.

    It's generally much more practical to dilute the water to reduce the CYA level. Thereafter, it is very easy to prevent CYA from climbing by simply limiting the use of stabilized chlorine products (and, of course, not adding more than the needed amount of pure CYA initially). Prevention is far easier than the cure.

    Quote Originally Posted by Geonapa
    The CYA was way high so i did a water change. Now i have stains :(
    As you noted in this post, you used algaecide with copper in it. Copper can stain and though the brown stains you got were more likely to be iron from the fill water, you nevertheless want to avoid adding metal to your pool. If you manage your pool so that you don't get the CYA high again, then you shouldn't need to change the water. However, there will still be a buildup of salt and other substances so you will want to dilute your water periodically, but if you have summer or winter rains then you can use that for water dilution (along with backwashing if you have a filter that gets backwashed). You should have your fill water tested for metals (especially iron) and if present then consider methods to handle that -- a water filter (ion exchange resin or similar product) for the fill line, use of a metal sequestrant, or possibly using CuLator.
    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

    Re: If i let my FC dropped to zero

    Thanks for the information
    Point understood
    31,000 liters concrete vinyl pool - 1hp pump - Monarch 85kg sand filter - 2 skimmers, 1 main drain, 2 jets - safety fence - 12V leds lights par56 .[/i]

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