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Thread: Brushing While Draining

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    Brushing While Draining

    Does it make sense to continually brush the pool walls while draining to reduce CYA? One reference I found (then lost) indicated that CYA stuck to walls as the water level dropped, so the best way to reduce CYA was to brush it back into the remaining water still to be drained. Is there anything to this?
    Jaywalker

    In-ground, 11,000 gallon, plaster, in-line trichlor pucks or BBB bottled chlorine, 1.5 HP pump @ ~100 gallons/minute, cartridge filter

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    Re: Brushing While Draining

    I don't think so. However, we have had several reports of CYA remaining high after a drain that should have lowered it to a more suitable level.

    It has been hypothesized (but I don't think definitively resolved) that it could be the result of CYA clinging to the hard surfaces (pipes, walls, etc) of the pool and that it is then released back into solution when the CYA is diluted.

    While I suppose that could be the case, I would suggest a far more likely reason for that observation is the innaccurate test result for high CYA in the first place.

    So, if your first test for CYA is a result of 100, I believe it could easily be 120 or perhaps even more because the test is not very accurate at that level. The pool owner then does a 50% drain and gets a reading of 60-70 and, believing the 100, can't figure out why he/she didn't get 50.

    My personal experience (having to add CYA almost every spring through my own neglect) is that my dosage calculations come out fairly accurate and I have never had to adjust for any "residual".

    Others may have had a different experience.
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    Re: Brushing While Draining

    Quote Originally Posted by Jaywalker
    Does it make sense to continually brush the pool walls while draining to reduce CYA? One reference I found (then lost) indicated that CYA stuck to walls as the water level dropped, so the best way to reduce CYA was to brush it back into the remaining water still to be drained. Is there anything to this?
    For the CYA to get "stuck" to the walls it would first have to drop out of solution, accomplished in the CYA test by the addition of melamine. I do infrequent partial drains on my pool and estimate the water volume fairly closely so I know how much calcium, bicarbonate, CYA and chlorine to add when I'm done refilling. The drop in CYA correlates to the amount of water I've drained. duraleigh's suggestion of testing error as a reason some folks with high CYA suspect that the CYA is 'hanging on' makes sense to me.
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    Re: Brushing While Draining

    Quote Originally Posted by duraleigh
    IWhile I suppose that could be the case, I would suggest a far more likely reason for that observation is the innaccurate test result for high CYA in the first place.

    So, if your first test for CYA is a result of 100, I believe it could easily be 120 or perhaps even more because the test is not very accurate at that level. The pool owner then does a 50% drain and gets a reading of 60-70 and, believing the 100, can't figure out why he/she didn't get 50.
    I concur. The only way to get a reading over 100 is by dilution, which adds a source of error. And I discovered last week that temperature makes a huge difference in the CYA test. I dilute 50:50, and have been watching my CYA drop from 220 (est) to 160/180. Until I read something here that caused me to use warm water to dilute. The test came in squarely at 200. Consistently. Whereas before it seemed to fluctuate as I poured it back and forth repeating the test. This was probably as it warmed up sitting in the sun on a white patio table.

    And, yes, I know that's too high. I'm working on it. Draining enough to bring it down would use 4X as much water as I use in a month - sure to bring down the wrath of the water company this year.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Brushing While Draining

    Quote Originally Posted by duraleigh
    ...My personal experience (having to add CYA almost every spring through my own neglect)...
    I have read a few places (including here) where CYA goes low over the winter. Does CYA break down once the chlorine is gone? How does it decrease if the only way to lower it (as I have been told) is to drain/fill?
    TFP Method Advanced Intermediate
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    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by duraleigh
    ...My personal experience (having to add CYA almost every spring through my own neglect)...
    I have read a few places (including here) where CYA goes low over the winter. Does CYA break down once the chlorine is gone? How does it decrease if the only way to lower it (as I have been told) is to drain/fill?
    Apparently there is some soil-borne bacteria that eats CYA. The Chlorine keeps it in check. Once Chlorine disappears, it can go to work.

    Wouldn't you love to get a jug of someone's bacteria-laden water to use as a starter, like sourdough yeast, to rid the pool of the CYA? Let it chowdown then shock it when it's at a good stopping point.

    We can dream, can't we?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Brushing While Draining

    Quote Originally Posted by Richard320
    ...Wouldn't you love to get a jug of someone's bacteria-laden water to use as a starter, like sourdough yeast, to rid the pool of the CYA? Let it chowdown then shock it when it's at a good stopping point...
    Sounds good to me (after I just did a 50% drain). Maybe that's how we make our fortune. Richard & Sven's Magic CYA Down. $59.95 / quart at Leslie's right next to the Tri-Chlor tabs.
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by Richard320
    ...Wouldn't you love to get a jug of someone's bacteria-laden water to use as a starter, like sourdough yeast, to rid the pool of the CYA? Let it chowdown then shock it when it's at a good stopping point...
    Sounds good to me (after I just did a 50% drain). Maybe that's how we make our fortune. Richard & Sven's Magic CYA Down. $59.95 / quart at Leslie's right next to the Tri-Chlor tabs.
    Or maybe just hire a good R/O company to save the majority of the water, lower CH and CYA (as well as the other TDS present) and get water like you really want from the start in a quick, simple process Hmmm, somebody should look into this..........

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    Re: Brushing While Draining

    CYA can crystalize somewhere and then redissolve later. This isn't common, but it does happen, usually after CYA levels have been astronomically high. I don't believe that it has been established exactly where CYA tends to crystalize, perhaps in the plumbing or within the surface of the plaster, but it does happen now and then. However, even if the hidden CYA is in the plaster, brushing doesn't help remove it.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Brushing While Draining

    Quote Originally Posted by simicrintz
    ...Or maybe just hire a good R/O company to save the majority of the water, lower CH and CYA (as well as the other TDS present) and get water like you really want from the start in a quick, simple process Hmmm, somebody should look into this..........
    ...and how much would such a process cost (order of magnitude), if someone were to look into it?
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Brushing While Draining

    If the CYA has somehow crystallized and therefore dropped out of solution, wouldn't it not appreciably affect the test results?

    I liken it to dropping a trichlor puck into the pool and just letting it sit there - just becaused the puck (when dissovled) adds x amount of chlorine to the water, you wouldn't necessarily get a reading of FC+x just because you technically have the puck "in" the water.

    The explanation given by duraleigh seems most likely.
    45,180 gallon 26' x 53' IG Vinyl, irregular shape. Hayward sand filter / pump. Polaris AutoClear SWG, supplemented with a Hayward Automatic Chlorinator (In-Line). Hayward 400K BTU heater. Paramount "turnover" system. Polaris 480 PRO cleaner.

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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by simicrintz
    ...Or maybe just hire a good R/O company to save the majority of the water, lower CH and CYA (as well as the other TDS present) and get water like you really want from the start in a quick, simple process Hmmm, somebody should look into this..........
    ...and how much would such a process cost (order of magnitude), if someone were to look into it?
    Undoubtedly more than it would cost to use tap water, or trucking water in, for that matter.

    Although I am only assuming and have no experience with the cost of such a service.
    45,180 gallon 26' x 53' IG Vinyl, irregular shape. Hayward sand filter / pump. Polaris AutoClear SWG, supplemented with a Hayward Automatic Chlorinator (In-Line). Hayward 400K BTU heater. Paramount "turnover" system. Polaris 480 PRO cleaner.

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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by simicrintz
    ...Or maybe just hire a good R/O company to save the majority of the water, lower CH and CYA (as well as the other TDS present) and get water like you really want from the start in a quick, simple process Hmmm, somebody should look into this..........
    ...and how much would such a process cost (order of magnitude), if someone were to look into it?
    This recent thread discussed this:
    http://www.troublefreepool.com/post151243.html#p151243
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by simicrintz
    ...Or maybe just hire a good R/O company to save the majority of the water, lower CH and CYA (as well as the other TDS present) and get water like you really want from the start in a quick, simple process Hmmm, somebody should look into this..........
    ...and how much would such a process cost (order of magnitude), if someone were to look into it?
    Your pool, locally, $375.00. CH to 200 ppm, CYA to 30 ppm, TA to 30 ppm, TDS to 700 ppm. Way better than comes from our tap!

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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by duraleigh
    ...My personal experience (having to add CYA almost every spring through my own neglect)...
    I have read a few places (including here) where CYA goes low over the winter. Does CYA break down once the chlorine is gone? How does it decrease if the only way to lower it (as I have been told) is to drain/fill?
    Richard (chem geek) has sometimes talked about a process where CYA is slowly oxidized by chlorine, however this effect was mainly seen is spas due to the higher temps. So, midsummer pool temps into the 90s might see a slow drop in CYA from this effect as well (on the order of a few ppm per month). That doesn't explain significant winter drops, really, but I thought I'd bring it up because some ways that CYA behaves aren't necessarily well understood.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: Brushing While Draining

    To read about CYA destruction, start with the following thread. There's also a link to a discussion in the Deep End forum that provides additional detail.

    cya-gone-t11559.html
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    Re: Brushing While Draining

    Quote Originally Posted by svenpup
    Quote Originally Posted by Richard320
    ...Wouldn't you love to get a jug of someone's bacteria-laden water to use as a starter, like sourdough yeast, to rid the pool of the CYA? Let it chowdown then shock it when it's at a good stopping point...
    Sounds good to me (after I just did a 50% drain). Maybe that's how we make our fortune. Richard & Sven's Magic CYA Down. $59.95 / quart at Leslie's right next to the Tri-Chlor tabs.
    Based on this post someone already had the same idea.

    Guess I will keep my day job.
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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