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Thread: Possible chlorine demand issue

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    Possible chlorine demand issue

    Hello all, new pool owner here, and looking forward to becoming an active member!

    Purchased my house in early August, pool is 10-12 years old. I had a LARGE pine tree cut down that was next to the pool shortly after we moved in, and have been dealing with chlorine issues ever since.

    I've yet to start the BBB method, as the previous owner left me with a large amount of supplies, including an almost full bucket of 3" chlorine tabs.

    Anyways, fast forward, everything is basically perfect on the pool, with the exception of chlorine. The levels are constantly low, a week ago the pool was cloudy, we had just returned from out of town, so I took the water to be tested (yet to buy my own kit), nothing too crazy going on, except chlorine was .4.

    Added some acid, shocked, and added microfloc, 2 days later, clear as day. Take water to get tested again, chlorine is now .3, decide to shock it again last Friday, using the last of my smart shock from previous owner. Yesterday, test reveals all levels are good except chlorine is still only .4.

    They should be calling me today with the results of the chlorine demand test, I've got to figure it's going to reveal I have a demand issue, but figured it couldn't hurt to ask on here first. If I do, how do I solve it?
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    duraleigh's Avatar
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    Re: Possible chlorine demand issue

    Welcome to the forum.

    What is your CYA level?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Possible chlorine demand issue

    I left the print out at the store yesterday, so I can't say for sure but it was within the acceptable range
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Join Date
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    Re: Possible chlorine demand issue

    Welcome to TFP!

    We need some test results from you. We need FC, CC, CYA, pH, CH, and TA. You can get the pool store to run them for you but there really isn't any consistent degree of accuracy that you can expect from their testing methods. But, it's a start. You also need your own high quality test kit so I would suggest getting yourself a TF-100 from tftestkits.net or a Taylor K-2006.

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    linen's Avatar
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    Re: Possible chlorine demand issue

    Welcome to tfp, MrJonMan

    Quote Originally Posted by MrJonMan
    everything is basically perfect on the pool, with the exception of chlorine.
    Is this perfect as judged by the pool store? Pool stores not only are very inconsistent on testing accuracy, their "suggested levels" often lead to trouble (and more product they stock bought by the pool owner). I would guess your cya level is very high due to the puck usage and the reason your chlorine is low is that you were not using enough due to your high cya, and now you have algae. See: http://www.troublefreepool.com/pool-..._chlorine_pool and http://www.troublefreepool.com/pool-...ater_chemistry and http://www.troublefreepool.com/pool-...ya_chart_shock

    What does your water look like now?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Possible chlorine demand issue

    Sorry for the delayed response, yesterday was busy.

    Yes, levels are "perfect" per the pool store test results. I'm unable to find my most recent water test (maid came and stuck it somewhere), however, according to them, my CYA level wasn't high....I know they can't be trusted.

    Also, I have little to no algae in it, when I do, it shows up near the steps in both the pool and spa, but again, nothing major.

    I've ordered a REAL test kit as recommended, but obviously that doesn't help me until it arrives. I will call the store in regards to my demand test today since I've yet to hear back.
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Re: Possible chlorine demand issue

    Oh and the chlorinator is working properly, currently set on 4.5. Also, since there is almost no chlorine in the water, I've put a tab in both skimmers.
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Mod Squad jblizzle's Avatar
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    Re: Possible chlorine demand issue

    You are likely going to find that your CYA is high, and continuing to use the tablets is going to make the problem worse. Also, unless you have the pump running continually, you should never put the tablets in the skimmer.

    I would suggest start using liquid chlorine / bleach until you know whether you can use the extra CYA the tabs are adding.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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  9. Back To Top    #9

    Re: Possible chlorine demand issue

    Last test results from store:

    CYA: 107
    TC: 0.4
    FC: 0
    PH: 7.3
    Alkalinity: 104
    Adj. Alk: 72
    Hardness: 249
    Optimizer: 90

    Demand test said I need 52 bags. They said to avoid that, will dilute the water by doing the following:

    1. Let water sit stagnant for 1hr
    2. Put a sock on the end of the hose with a rock in it & put it at bottom of pool, let run for 4hours.
    3. Put 1 crushed tab in each skimmer & let pump run over night.
    4. Retest for demand
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Re: Possible chlorine demand issue

    They said by doing this, they hope to get it down to about 12 bags

    I'm guessing they're meaning bags of shock?
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Mod Squad Bama Rambler's Avatar
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    Re: Possible chlorine demand issue

    With your CYA already sky high and your CH at 250 you shouldn't be adding any so called bags of "shock".

    You really need your own test kit. and then you cna take control of your pool.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Possible chlorine demand issue

    Well I've ordered a kit but that doesn't help me until it gets here sometime next week.

    It says 30-200 is acceptable CYA range, guess that's incorrect?
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Smykowski's Avatar
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    Re: Possible chlorine demand issue

    Quote Originally Posted by MrJonMan
    It says 30-200 is acceptable CYA range, guess that's incorrect?
    Very. The pool stores don't understand the relationship between FC and CYA.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

  14. Back To Top    #14

    Re: Possible chlorine demand issue

    Is there anything I can do so that it's swim-able this weekend? I'm running out of pool weather weekends!
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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    Mod Squad jblizzle's Avatar
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    Re: Possible chlorine demand issue

    First, you need to read Pool School to learn about the chemistry and stop going to the pool stores for bad advice. You need to learn that those tablets are what is causing your problems.

    What you should do:
    1. Add one 121oz bottle of 8.25% bleach every day while waiting for kit
    2. Do a full set of tests ... determine the CYA
    3. Replace enough water to get the CYA down to the recommended 30-50ppm range
    4. Follow the SLAM Process until you pass the 3 criteria

    What does your water currently look like? Do you have ANY test right now?
    If you can clearly see the bottom, then just keep adding bleach to maintain around 5ppm and the pool is generally safe to swim in (although technically, we would normally recommend having the FC > minimium for you CYA level based on the FC/CYA Chart which for you is likly > 7ppm, but I know you do not have the ability to test that high.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  16. Back To Top    #16

    Re: Possible chlorine demand issue

    Quote Originally Posted by jblizzle
    First, you need to read Pool School to learn about the chemistry and stop going to the pool stores for bad advice. You need to learn that those tablets are what is causing your problems.

    What you should do:
    1. Add one 121oz bottle of 8.25% bleach every day while waiting for kit
    2. Do a full set of tests ... determine the CYA
    3. Replace enough water to get the CYA down to the recommended 30-50ppm range
    4. Follow the SLAM Process until you pass the 3 criteria

    What does your water currently look like? Do you have ANY test right now?
    If you can clearly see the bottom, then just keep adding bleach to maintain around 5ppm and the pool is generally safe to swim in (although technically, we would normally recommend having the FC > minimium for you CYA level based on the FC/CYA Chart which for you is likly > 7ppm, but I know you do not have the ability to test that high.
    Have no tests of my own, just the unreliable pool stores.

    The water looks great, I mean essentially perfect. Clear as day, no algae or anything.
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

  17. Back To Top    #17
    Mod Squad jblizzle's Avatar
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    Re: Possible chlorine demand issue

    Then just add a bottle of bleach a day until the test kit arrives.
    Which one did you order?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  18. Back To Top    #18

    Re: Possible chlorine demand issue

    K-2006
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

  19. Back To Top    #19
    Mod Squad jblizzle's Avatar
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    Re: Possible chlorine demand issue

    Well, you do not get a lot of CYA regent with that kit. So I would start with a 50/50 mix of pool and tap water, then add the reagent, then do the reading with your back to the sun and the tube at waist level. Then double the result. You can pout back and forth a few times.

    If it is still near 100ppm, dump out half the mix and add more tap water and try again, multiplying by 4.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  20. Back To Top    #20

    Re: Possible chlorine demand issue

    Turns out my dad has an unused Taylor k-2005 test kit, worth using to see my levels?
    20k gallons
    In ground plaster pool
    Hayward Pro-Grid DE4820, Pentair Whisperflow 2hp
    Spa

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