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Thread: Re: How did the CYA levels get so high in my pool ?

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    Join Date
    Aug 2014

    Re: How did the CYA levels get so high in my pool ?

    Thank you so much!! So glad I found this site.
    I've been fighting algae all summer - I'd test the water - chlorine and PH were fine. Then I splurged and bought a test kit with CYA test in it. Found the problem... CYA was over 100!! And I had been using the tablets for the last year. No wonder pool was great last year and such a pain this year. While I'm not thrilled to have to replace the water to get the levels normal... its much cheaper than a new filter, which is what I swore I needed ( I hate it when hubby is right!!) thanks again!!
    38900 gallons ,IG ,Gunite, sand filter ( swim quip from the 60's), pump: Hayward SP2610X15 1.5 HP single speed, pool installed?? late 60's, re- surfaced October 2012

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    swoopman's Avatar
    Join Date
    Jul 2014
    Annapolis, MD

    Re: How did the CYA levels get so high in my pool ?

    Welcome to TFP!

    New here too and just finished a drain and fill due to high CYA. It is well worth the effort - the water is clear and so much easier to maintain. Make sure you understand your ground water tables and the risk of floating pool shell before draining a lot of water at one time.

    Have you done the diluted CYA test so you have a good handle on how much to drain?
    Scroll down to CYA and see step #9.
    TF-100 Test Kit
    22,000 gallon, 20x40 kidney-shape IG plaster pool built in 1986
    Nautilus NS-36 DE filter, Hayward Self Prime Super Pump 1HP
    Polaris Automatic Pool Cleaner, PB4-60 3/4 HP pump

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    Mod Squad JVTrain's Avatar
    Join Date
    Feb 2014
    Central Minnesota

    Re: How did the CYA levels get so high in my pool ?

    You've learned the hard way that continued use of any type of reasonably priced solid chlorine, whether it's trichlor tablets, dichlor granules or cal-hypo, has adverse side effects. I say reasonably priced as Lithium Hypochlorite doesn't have these side effects but is VERY expensive. With a proper test kit and the knowledge contained in Pool School here on this site, you can take control of your pool.

    Which kit are you testing with?

    I do recommend doing the CYA test with the dilution instructions to get a better idea how high it is but it's not essential. You know the CYA is way too high. Drain as much as you can safely with your pool. With a plaster surface, you don't want it exposed to hot sun without water for very long. Drain and refill as quickly as you can if it's going to be warm/sunny. Also, try to get a handle on the water table in your area. As swoopman mentioned, if you have a high water table, you could float or crack your pool if there is no pressure on the pool walls from the inside from water. Most areas this shouldn't be in issue, but if you happen to know how deep wells are usually in your area, that can help. You can retest after refilling.
    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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