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Thread: CYA Disappears?

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    happyheathen's Avatar
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    CYA Disappears?

    I have been having a Edit: PM sent, Butterfly problem keeping the silly OTO anywhere near yellow.
    I drug out the K-2006 and ran the CYA (disappearing dot) test 3 times - twice using one bottle of reagent, the third with the unused bottle.

    In all cases, there was little or no cloudiness - I could fill the entire tube and the dot was visually unobstructed.

    I seem to be out of CYA in the garage, so off to the store - but...

    HOW did the CYA disappear? Is that reagent volitile to the point that 2 year old stuff is inert?

    I now have mustard algae, and am using something Home Depot sells as 20,000 Gallon Shock - 2.25 oz (1/8 of a cup) is supposed to raise FC by 1 ppm in 10,000 gal.
    I just dumped 7 oz. in and ran the pump for 2 hours - the OTO is off the scale, but the south wall still shows yellow (I had just wire-brushed it before adding the HD stuff.)

    If it turns out I have been trying to chlorinate 15,000 gal in the Sacto sun (105F) with no CYA, it would explain a lot.

    It would NOT explain the complete lack of CYA (was 50 a year or so ago). We have a drought (you may have heard), so rainwater is not the culprit.

    Ideas?
    Dave
    Sacramento
    1980's 15,000 Gal IG Plaster; 1 1/2 hp Hayward Northstar; Hayward Swimclear C3025 Cartridge Filter (325 sq ft, nom.); Pentair Legend; Polaris PB4-60; Equipment 40' from pool. p.s.: it's an aye-aye.

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    Mod Squad tim5055's Avatar
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    Re: CYA Disappears?

    No,idea where it went, but be careful with how much CYA you add, the 20,000 gallon shock is trichlor and added At least some CYA
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: CYA Disappears?

    Yes its a drought. But we got rain last winter. I had to partially drain my pool a couple of times to prevent an overflow. I dropped my CYA from 60 to 40 over the winter. You may also have bacteria eating your cya and turning it into ammonia. Does your pool have a very faint ammonia smell?
    22k gallon IG pebblefina, Jandy 1.5 HP VS, Jandy CV Cartridge filter, Fafco solar panels, Polaris 360 supply side cleaner, waterfall

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    Re: CYA Disappears?

    Was the pool let go at any time over the winter so that the FC went to 0? If so, then bacteria can convert the CYA to ammonia or to nitrogen gas. If to ammonia, you would have seen a very large chlorine demand not just during the day but anytime you added chlorine the FC would get to zero within minutes. If it went to nitrogen gas, then the CYA would be lower (or gone) but you would have no unusual chlorine demand except for loss of chlorine during the day due to the low (or no) CYA.
    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
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    Re: CYA Disappears?

    Thanks!
    That explains it - I don't use the pool (may try again - can't swim due to phobic reaction to water), I just try to keep it clean enough that no algae or mosquitoes appear.

    The ammonia option - would that be liquid or gas? I detect no odor.

    I will need 377 POUNDS of salt to use a chlorine generator? That was a bit of a surprise.

    I fully expect the OTO test to be entirely adequate by noon - it was off the scale deep yellow immediately after the Trichlor.
    Dave
    Sacramento
    1980's 15,000 Gal IG Plaster; 1 1/2 hp Hayward Northstar; Hayward Swimclear C3025 Cartridge Filter (325 sq ft, nom.); Pentair Legend; Polaris PB4-60; Equipment 40' from pool. p.s.: it's an aye-aye.

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    happyheathen's Avatar
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    How do I make my CYA disappear?

    Split by moderator from HERE due to hijacking and merged into your related topic. Keep related discussions together. jblizzle

    I mentioned in an earlier thread that I had gone from CYA 50 to CYA 0. The culprit was ID'd as having let the FC go to 0.

    In adding CYA, I overshot to a level of 100 (Taylor 2006, Read directly under a 60 watt incandescent (range hood)).
    Again, massive drought, and I have no use for used pool water, so I am NOT draining.

    Since I don't use the pool, just want it clear and clean looking, I plan to let the chlorine drop to 0.

    Q: Once there (another 2-3 days in this sun), how quickly will the CYA turn in to something not CYA? I don't have much reagent left, so testing every day is not optimal, if someone can give me guidance on when to expect 0.

    OTO shows about .3 (but with a CYA of 100, that is obviously useless).

    Is OTO close enough for 0? It's worthless for over 7, but what about the low end?

    As always, thanks for any feedback
    Dave
    Sacramento
    1980's 15,000 Gal IG Plaster; 1 1/2 hp Hayward Northstar; Hayward Swimclear C3025 Cartridge Filter (325 sq ft, nom.); Pentair Legend; Polaris PB4-60; Equipment 40' from pool. p.s.: it's an aye-aye.

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    Mod Squad jblizzle's Avatar
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    Re: Dissapearing FC and high CYA

    It does not work that way.

    The FC needs to drop to 0 for a prolonged period of time and then a certain bacteria needs to somehow get in the pool and convert the CYA to something else (like ammonia). Remember, we only see this typically happening in some pools that are neglected over the winter. There is no way to guess when the CYA will start to be converted, how long it will take, or whether it will happen at all.
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    Re: How do I make my CYA disappear?

    Quote Originally Posted by happyheathen View Post
    Again, massive drought, and I have no use for used pool water, so I am NOT draining.

    Since I don't use the pool, just want it clear and clean looking, I plan to let the chlorine drop to 0.
    IMHO ... If you let the FC go to zero for a few days or weeks you're more likely to end up with a green pond than a clear and clean looking pool.
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    Re: CYA Disappears?

    Thanks!

    I'll just let it go until mosquitoes appear and test again.
    Dave
    Sacramento
    1980's 15,000 Gal IG Plaster; 1 1/2 hp Hayward Northstar; Hayward Swimclear C3025 Cartridge Filter (325 sq ft, nom.); Pentair Legend; Polaris PB4-60; Equipment 40' from pool. p.s.: it's an aye-aye.

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    Re: CYA Disappears?

    Since I don't use the pool, just want it clear and clean looking, I plan to let the chlorine drop to 0.
    That simply won't work. Chlorine is what keeps your pool clear. read "The ABC's of Pool Water Chemistry" up in Pool School
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: How do I make my CYA disappear?

    Quote Originally Posted by kiss4afrog View Post
    IMHO ... If you let the FC go to zero for a few days or weeks you're more likely to end up with a green pond than a clear and clean looking pool.
    While that generally is true, it is certainly possible for the bacterial conversion to happen quite rapidly over a matter of days and it need not be over the winter -- just having the FC get to 0. See It Can Happen to Anyone - Zero Chlorine, CYA--->Ammonia and you can see that this occurred with around 20-30 ppm CYA degraded over a period of around 3-4 days and then the pool recovered with adding lots of chlorine over the next few days (details in this post).
    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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