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Thread: Remove mold (or ?) in skimmer/return lines

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    Remove mold (or ?) in skimmer/return lines

    I think i have something in my lines that is eating FC. I have cleaned the light niche, step screw cover panels, ladder, and still having difficulty maintaining FC. CC is around 0.5. When i was using Baquacil I cleaned them using LineClean as mentioned in this old thread: Baquacil Cloudy Pool/White Water Mold - SOLVED. But i'm not sure if that product is compatible with chlorine/cya. I think the LC product is similar to MSP. Does anyone know if i can add use MSP safely without any negative effects? [edit-or what is the safest max concentration i can pour into the skimmer?] Or have a better suggestion? Thanks
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Mod Squad pooldv's Avatar
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    Re: Remove mold (or ?) in skimmer/return lines

    Perform the Overnight FC Loss Test (OCLT) to see if there is something growing in the pool. If it doesn't pass then SLAM the pool to get rid of it, Pool School - SLAM - Shock Level And Maintain
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    Re: Remove mold (or ?) in skimmer/return lines

    Thanks but thats i what i have been trying to do and cant pass the OCLT. SLAM consuming nearly a case an hour during daylight so not doing that. hence my question.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Mod Squad pooldv's Avatar
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    Re: Remove mold (or ?) in skimmer/return lines

    Do you mean potassium monopersulfate (MPS)? No, it will not do a better job than chlorine/bleach and the SLAM process.

    This snip from here, Pool School - Definitions and Abbreviations
    Potassium Monopersulfate
    A non chlorine oxidizer or 'shock'. It is acidic and will cause lower pH and TA. It adds sulfates to the water. Will not break down CC but helps prevent it from forming when used on a regular basis. It will interfere with TC and CC tests unless special reagents are used in testing since it WILL test as CC! A good choice to use in indoor pools that are not exposed to sunlight but really has no advantage in an outdoor pool. It is only an oxidizer and NOT a sanitizer and should not be used as such.

    More on MPS here,
    Chemistry of Chloramines - indoor commercial pool
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Remove mold (or ?) in skimmer/return lines

    Did you already complete the baqua conversion or is that what you are doing now?
    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: Remove mold (or ?) in skimmer/return lines

    I am convinced the baqua conversion is complete. in my opinion, the reason i cannot pass the OCLT is due to stubborn, residual mold (or?) that does not consist of biguanide. and since i have cleaned as much as i can access, the next place to get is in the pipes. jmo of course.

    So in order to attack inside the pipes at a much higher level of chlorine in the pool water, what is the maximum strength of chlorine i can add to the skimmer-either directly or just in front of skimmer? without damaging equipment, seals, etc. For example, baquacil directions for additions of 27.5% hydrogen peroxide were to pour it in front of skimmer opening. This would of course dilute the concentrated solution before it entered the pipes. How much dilution? i dont know but would hazard a guess of at least 4 times.

    Any suggestions? Thanks.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Mod Squad tim5055's Avatar
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    Re: Remove mold (or ?) in skimmer/return lines

    If the baqua conversion is complete, have you replaced the media in the filter?
    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: Remove mold (or ?) in skimmer/return lines

    For starters, can you please post up a complete set of results including your last OCLT results. The chlorine used during the Baqua conversion is likely high enough to take care of anything hiding in your pipes. If you can post up a set of results and maybe a photo of your pool we can help you find the cause of the increased FC demand.

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    Re: Remove mold (or ?) in skimmer/return lines

    Quote Originally Posted by tim5055 View Post
    If the baqua conversion is complete, have you replaced the media in the filter?
    yes, with glass media
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Remove mold (or ?) in skimmer/return lines

    Quote Originally Posted by Leebo View Post
    For starters, can you please post up a complete set of results including your last OCLT results. The chlorine used during the Baqua conversion is likely high enough to take care of anything hiding in your pipes. If you can post up a set of results and maybe a photo of your pool we can help you find the cause of the increased FC demand.
    most recent OCLT 5 and 6 ppm.
    other recent results:
    FC 2 in am, 0 late afternoon. add chlorine in evening to obtain 6 ppm (and yes i know this would equal oclt of 4, but my oclt of 5 and 6 are from shock levels)
    CC from zero to less than 1.
    TA about 150
    pH 7.5 (just successful in raising it by aeration)
    CYA 40-50

    pictures of pool from each end here:
    pool pic1.jpg - Google Drive
    pool pic2.jpg - Google Drive
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Remove mold (or ?) in skimmer/return lines

    Quote Originally Posted by pookiesunshine View Post
    most recent OCLT 5 and 6 ppm.
    other recent results:
    FC 2 in am, 0 late afternoon. add chlorine in evening to obtain 6 ppm (and yes i know this would equal oclt of 4, but my oclt of 5 and 6 are from shock levels)
    CC from zero to less than 1.
    TA about 150
    pH 7.5 (just successful in raising it by aeration)
    CYA 40-50
    I am confused with your OCLT results, what does "OCLT 5 and 6 ppm" mean?

    What does this mean also "FC 2 in am, 0 late afternoon. add chlorine in evening to obtain 6 ppm (and yes i know this would equal oclt of 4, but my oclt of 5 and 6 are from shock levels)"

    The OCLT is conducted overnight. Take a chlorine reading after the sun goes down. Take a second reading before the sun comes up. The difference tells if you pass or fail.

    You have 50 CYA so if you are in a SLAM your FC should be upwards of 20ppm, not down around 2.
    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: Remove mold (or ?) in skimmer/return lines

    OCLT 5 and 6 means that my loss overnight was 5 to 6 ppm.
    I get FC around 2 when i test in the morning; by evening it is zero. I have been targeting FC of around 6 when i add chlorine at night, so when i get FC 2 in the morning, that equates to a loss (what i referred to as OCLT loss) of about 4ppm.
    And yes, i know the SLAM target is 20, but i cannot maintain that during daylight hours even using a case of shock every hour, so i quit the SLAM thinking i might try to use higher chlorine or other oxidizer to get at what ever is in the pipes, if anything.

    So, again, does anyone know what the safest level of chlorine i can add either directly to skimmer or just in front of skimmer opening? Can i add 12.5% chlorine this way, or is that just too concentrated for equipment? Thanks.
    and Tim5055, sorry, i did not see your response til just now.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Mod Squad pooldv's Avatar
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    Re: Remove mold (or ?) in skimmer/return lines

    Here is the Chlorine CYA Chart that shows shock level for CYA levels.
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    Re: Remove mold (or ?) in skimmer/return lines

    Quote Originally Posted by pooldv View Post
    Here is the Chlorine CYA Chart that shows shock level for CYA levels.
    That gives me the average level in the pool, not what i can add safely to the skimmer. When dosing to shock level, chlorine is added in front of the return jets to rapidly dilute it. I want concentrate inside the pipes.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Remove mold (or ?) in skimmer/return lines

    Quote Originally Posted by pookiesunshine View Post
    So, again, does anyone know what the safest level of chlorine i can add either directly to skimmer or just in front of skimmer opening? Can i add 12.5% chlorine this way, or is that just too concentrated for equipment? Thanks.
    and Tim5055, sorry, i did not see your response til just now.
    A large part of this depends on your CYA level. If you have very low CYA then adding liquid chlorine to your skimmer can do great damage to various parts of your equipment. Even with normal CYA you still are taking a risk of damaging your equipment.


    That said, it really does sound like you're slightly off track here. You were attempting to convert from Baqua to Chlorine and all went well until you hit the OCLT. You are failing this still correct? If so, then your conversion is not complete and CYA should not be added yet to the water. By doing this you will circulate water with VERY high chlorine levels through the plumbing thus breaking down anything that's consuming your chlorine in your pipes. That said, you have already added CYA to the water and that cannot be undone. So what's next?

    If it were my pool and I was seeing my FC levels drop 3-4ppm overnight I too would suspect there to be BaquaGoo remaining in the plumbing.......especially after looking at your photo's (gorgeous pool by the way). In this case I would raise my chlorine level to Mustard Algae levels and maintain it for a few days while running the pump 24/7. This should help break down the last bit of whatever is increasing your chlorine consumption and allow you to pass the OCLT. Your target levels of 6 is simply to low and by simply dumping chlorine into your skimmer you will risk damaging various parts to your equipment pad.

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    Re: Remove mold (or ?) in skimmer/return lines

    Thanks, Leebo, I was concerned about damaging equipment. I will try Mustard level when i see several days of cool, cloudy weather coming. I cannot hold FC on sunny days, way too much chlorine required. You did answer my question.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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