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Thread: Pool Water Change by Newbie!!How much % to change and why??

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    Pool Water Change by Newbie!!How much % to change and why??

    Pool Water Change!! How much % to change and why??

    My Pool water hasn;t been changed in over 8+ years and have noticed its hard to keep up with chemical demand.

    I have to ad over 200% acid of what i normally have been and less chlorine to keep the Ph level in sync.

    I'm installing a new Intelliflo Pump and Quad 60 DE filter as my equipment is from 1972 and very ineficient.

    1....How much pool water do i drain and refill?

    2...Is there a test i can do to tell what percentage to drain?

    3...Why do we have to drain our pools?

    4...Do i have to be concerned about "Pool Popout" in my So. California area? We have had some rainfall lately.

    I would like to put in an inline chlorinator but my funds are depleted because of Pentair equipment purchase. Is there an ecomomical way to put in chemicals better than by hand until i have the funds to go to automated salt water system?

    Thanks .........Gman

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    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana

    Re: Pool Water Change by Newbie!!How much % to change and why??

    Quote Originally Posted by gman66
    3...Why do we have to drain our pools?
    You don't have to routinely, but if you are using pool store chemicals you may have high CYA, high calcium or both. Get a good test kit and analyze your water to find out what you need to do. A member here sells a good one at, or you can buy a Taylor K2006. Any lesser test kit doesn't give you enough information to maintain a pool well.

    I would advise against regular use of an inline chlorinator. Trichlor adds CYA rapidly to the water which can lead to overstabilized water. Most of use that don't have saltwater systems use liquid bleach poured in by hand, and only use our chlorinators when we are on vacation.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    What is CYA?

    Sorry..I'm a newbie to the short form lingo.


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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    CYA is cyanuric acid, often called stabilizer. The higher your CYA level the more FC you need to keep the algae away. Trichlor, the chlorine source used with tablet feeders, is "stabilized" with cyanuric acid. The more trichlor you use the higher the CYA level, the more you need to use and eventually you can't keep up and get algae.

    There is no need to change the pool water unless there is some specific problem. Get a full set of test numbers (at least FC, PH, TA, CH, and CYA) and we can tell you what you need to do. By far the best idea is to get a good test kit, such as the TF Test Kit, see the link in my signature, or the Taylor K2006. But if you are in a hurry you can start with test results from a pool store.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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