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Thread: dumped half pool, Cyanuric increased from 50 to 90

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    dumped half pool, Cyanuric increased from 50 to 90

    New pool in May. Mistakenly listened to local Pool Supplier clerks and was using tri-chlor floater with di-chlor for shocking. All that ,after pool install instructions advised me to add 1 LB "stabilizer" in skimmer at start-up. Water looked good for 6 weeks until it rained. Since then, I began fighting algae.
    Chems were FC:5, TA:5, CH:220, CYA:50, pH 7.6 so after two rounds of fighting algae in two weeks, I decided to dump over half the pool to get CYA to 30 to allow better chance to fight algae with affordable oxidizer level. Refilled, but failed to remove the floater containing 2 tablets of Trichlor and again mistakenly started with 1.5 lb di-chlor resulting in CYA of 90 CYA! It nearly doubled after diluting with ~7000 gallons of puclic well water! Now CYA:90, pH: 7.4 TA: 110, FC: recently dropped to 4, CH:200 87 degree water surrounded by no less than 50 trees in the back yard.
    Two problems to address: CYA and Algae.
    1) CYA: Most importantly where did that level come from? I have multiple consistent readings before and after so seems to pass measurement system analysis. Was it stuck in filter. I drained pool directly to waste via bottom drain. If I dump it again and remove all stabilzed chlorine sources, I fear what may result.
    2) Algae: Pump runs 24/7. I think it is mustard as it is just barely brownish near center drain at bottom, which is always on. It sweeps away easy. Pool looks barely cloudy. I do not want to use 12-13 bottles of bleach to shock it and then many more each week. So after 2nd refill in a week, theory is I could oxidize to 60% of resulting CYA level for a couple of days.
    How far off is my thinking? BTW, we are all septic systems here so water has no additional fees. Tends to be cheap although I still think wasteful to repeatedly dump it.
    CYA: considering dumping majority of pool to get rid of it and begin using bleach. But most importantly, I cannot understand how this level increased so drastically. Was i
    24' AG (13,600 gal), Sand filter, vynil, 1.5 HP, 60 GPM, since May 2012.

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    linen's Avatar
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    Re: dumped half pool, Cyanuric increased from 50 to 90

    Welcome to tfp, Humid

    How are you testing for cya? If it is test strips, then ignore your values, test strips are almost always wrong on cya. If your using the pool store, they often use strips...so same story.

    If you dont have an appropriate test kit, you need one. Here is a pool school article on test kits: http://www.troublefreepool.com/pool-...kit_comparison I like the TF-100, most bang for buck and very fast shipping.

    You need to do the shocking process. Most people who think they have mustard algae, actually don't. Once you complete the shocking process (it is a process not an application of some product), then if there are still problems we can help determine if it's Mustard algae.
    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: dumped half pool, Cyanuric increased from 50 to 90

    CYA test were all performed by watching for the black dot. Multiple people and locations had consistent result. Measurement error could enter if other problems would add to the clouding after reagent is added.
    So at 90 CYA, I require 35 ppm FC- current level 4 ppm = 31ppm at 13700 gal = ~7 gal bleach initial dose. Retest and keep adding til only slowly drops. I will search for threads on safe swim level to see if I wait 15-30 days for level to drop or if safety zone increases in proportion of CYA also since target is 10.
    24' AG (13,600 gal), Sand filter, vynil, 1.5 HP, 60 GPM, since May 2012.

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    Re: dumped half pool, Cyanuric increased from 50 to 90

    The problem with shocking with a level of 90 for the CYA is the amount of bleach required to do it. What is more of a problem is the amount of chlorine that will be needed to maintain the proper amount of chlorine at that level of CYA for a non SWG pool. If I were you, I'd dump half the water to get the CYA more reasonable and then go through the shock process.

    Most people here agree that you can swim in levels of chlorine that are up to shock value for your given CYA level.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
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    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Re: dumped half pool, Cyanuric increased from 50 to 90

    CYA: Most importantly where did that level come from?
    It can only get into your pool if you or someone put it there.....there is no other source.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: dumped half pool, Cyanuric increased from 50 to 90

    Quote Originally Posted by Humid
    I decided to dump over half the pool to get CYA to 30 to allow better chance to fight algae with affordable oxidizer level. Refilled, but failed to remove the floater containing 2 tablets of Trichlor and again mistakenly started with 1.5 lb di-chlor resulting in CYA of 90 CYA! It nearly doubled after diluting with ~7000 gallons of puclic well water! Now CYA:90, pH: 7.4 TA: 110, FC: recently dropped to 4, CH:200 87 degree water surrounded by no less than 50 trees in the back yard.
    Two problems to address: CYA and Algae.
    1) CYA: Most importantly where did that level come from?
    A small part of it came from the floater and the dichlor. But I can't figure out how you got from 60 to 90 either. Two 3 oz pucks of trichlor (assuming that size) shouldn't have added more than 1.8ppm of CYA to a 14000 gallon pool. The 24 oz of dichlor would have added another 6.5ppm - but the total there is under 10ppm. If the trichlor pucks were larger maybe they had something to do with it but unless you had more like 8 lbs of trichlor in the feeder I don't see it. Personally I can't see how even with what you added - you ended up OVER and not under the original value. In theory you dropped 30ppm and only picked up less than 10. You should by all rights be around 50ppm. Maybe the dichlor fairy came to visit several times?


    Quote Originally Posted by Humid
    2) Algae: Pump runs 24/7. I think it is mustard as it is just barely brownish near center drain at bottom, which is always on. It sweeps away easy. Pool looks barely cloudy. I do not want to use 12-13 bottles of bleach to shock it and then many more each week. So after 2nd refill in a week, theory is I could oxidize to 60% of resulting CYA level for a couple of days.
    How far off is my thinking? BTW, we are all septic systems here so water has no additional fees. Tends to be cheap although I still think wasteful to repeatedly dump it.
    CYA: considering dumping majority of pool to get rid of it and begin using bleach. But most importantly, I cannot understand how this level increased so drastically.
    [/quote]

    Dump it. If water is cheap - just do it. Be very careful and use pool calculator to determine how much stabilizer you need and avoid overdoing it. Sneak up on the number - start with 2/3rd's as much as you need and check it to be sure your calcs are correct.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

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