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Thread: CYA Degradation - Happen Once - Will it Happen Again?

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    happyheathen's Avatar
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    CYA Degradation - Happen Once - Will it Happen Again?

    As mentioned months ago, I OD'd the pool with CYA - it tests out at 100 ppm.

    Last year it started the winter at 50 and came out 0 - ammonia formation or some such reaction was the diagnoses here.
    We have a very serious drought out here, so draining 7000 gallons is not going to happen.
    One change: it now has a blue "solar" cover on it (hides all the algae growing).
    Aside from dumping a bit of bleach whenever I see mosquito larvae, it has no FC.

    What are the odds that the CYA will dissipate?

    Thanks 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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    Mod Squad JVTrain's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Since it's happened before, it's likely to happen again if you effectively have no FC. CYA is "known" to be converted to ammonia by some soil bacteria. With no FC, you let the bacteria live in the pool. Since it's happened before, you have the right conditions and biota for it to happen again. I'd say the odds are high.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    If it does happen again, please collect a water sample in a water-tight jar with no headspace (i.e. water filled to top) and I'll pay to have it analyzed. I've had conversations with the CEO and inventor/scientist at CuLator who doesn't believe the bacterial conversion theory because he doesn't think the conditions in pool water are anaerobic enough. The only way to be definitive about this is to analyze the water contents after such conversion to see what chemicals there are and, if still present, what bacteria or other biological microorganisms there are (some fungus is also known to do such conversion, but in soil and not reported in water).
    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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    Mod Squad JVTrain's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    I'm doing the closing on my pool this year so I likely won't have a conversion on my hands again, but if it happens, I'll let you know.

    From this spring:
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    happyheathen's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Will collect.
    Always thought there should be a thriving market for the right bug - draining is a much bigger effort than letting the pool go for a couple of months.

    - - - Updated - - -

    Just thought: Should I remove the cover?
    Last time it was completely exposed to air and sunlight - I can see a bug not being wild about sunshine, but the oxygen was much more accessible.
    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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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Nevermind - if we're after anaerobic, lack of free of oxygen would be ideal.
    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 Degradation - Happen Once - Will it Happen Again?

    Joel, did you measure that ammonia before you added any chlorine or was that after adding chlorine and you noticed a huge chlorine demand? Do you recall how much CYA was lost and how much FC needed to be added before an FC registered and held at least somewhat?

    Dave, the scientific literature says that anaerobic conditions are needed or at least low oxygen conditions as found in aerate activated sludge systems (< 4 mg/L; pools in equilibrium with oxygen in air would have 7+ mg/L) and that it's difficult to degrade CYA in aerobic conditions, but since we see something happening in quite a few pools and they don't all seem to be anaerobic (as far as we know) it's more important that this be reproduced, however that may occur.
    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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    Mod Squad JVTrain's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Quote Originally Posted by chem geek View Post
    Joel, did you measure that ammonia before you added any chlorine or was that after adding chlorine and you noticed a huge chlorine demand? Do you recall how much CYA was lost and how much FC needed to be added before an FC registered and held at least somewhat?
    I had a thread for my SLAM this spring. The ammonia issue, testing and bleach usage is fairly well documented. http://www.troublefreepool.com/threa...l=1#post627867

    I performed the chlorine demand bucket test as part of the process. http://www.troublefreepool.com/threa...ll=1#post54963

    EDIT - I don't know what the CYA was at before pool was closed as I took ownership in November of last year and did not test pool until spring thaw. It was a very cold winter, with thick ice over the entire pool. A good amount of snow melt also entered the pool.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Thanks. 136 ppm FC was a large demand from the bucket test, but the ammonia between 4 and 8 alone would require roughly 40-80 ppm and there may have been partially degraded CYA as well as some algae. 136 ppm FC would correspond to around 45 ppm CYA that could have been degraded.
    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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    Mod Squad JVTrain's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Quote Originally Posted by chem geek View Post
    Thanks. 136 ppm FC was a large demand from the bucket test, but the ammonia between 4 and 8 alone would require roughly 40-80 ppm and there may have been partially degraded CYA as well as some algae. 136 ppm FC would correspond to around 45 ppm CYA that could have been degraded.
    This is true assuming none of the ammonia degraded to other nitrogen species and/or gassed out as nitrogen so CYA could have been higher than that, if I remember the potential mechanism suggested.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    mas985's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Just to add an example, every winter/spring I experience about a 50% drop in CYA levels. During the winter, the water temp regularly gets below 50 F and the SWG shuts down so during this period, I just shut down the pump for a few weeks until the water gets above 50. But the downside of doing this seems to be a loss in CYA and large FC demand coming out of the low temps. But it is more than made up for by 0 run time and 0 energy cost for a few weeks.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Mark, since you are in my area, PM me before you open your pool and I can take a sample to get analyzed, especially if the CYA dropped and you have large chlorine demand and (before adding chlorine) measure ammonia.
    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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    mas985's Avatar
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    Re: CYA Degradation - Happen Once - Will it Happen Again?

    Ok. Also, I will try to remember to do a CYA test before and after to make sure there was a drop.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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