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Thread: ORP Figuring with a CAT 2000 and CYA

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    ORP Figuring with a CAT 2000 and CYA

    I Have a CAT 2000 sensor/auto feeder system for my pool. My goal is to maintain a standard of an ORP reading of 650-800. I know ORP measures in milivolts depending on a number of different chemical levels, but I don't know exactly how.

    So far, the only way to make my sensor read more than 250 is to have very high chlorine content. Right now, I'm at:

    FC=5.0
    CC=8.0+
    PH=7.0
    Alk=150
    CYA= no reading, have added 6kg in 3 weeks.

    Could it be the CYA measurement? I use the Taylor kit, but have never had any luck with measuring CYA.

    Any help with ORP and/or CYA testing with the Taylor kit? I tested after adding 4kg with a sock, with no results, then added another 2kg a week ago and rested today with no result. I run out of re-agent quickly, so should I keep adding Pool Stab until I get something?
    Andrew Carlson-Hastings Lake Bible Camp
    Sherwood Park, AB, Canada
    Outdoor IG Pool - 75,500 gal
    Plaster/tile lining - Sand filtered w/two filters
    2 variable speed pumps - Pool constructed in 1973

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    JasonLion's Avatar
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    May 2007
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    Re: ORP Figuring with a CAT 2000 and CYA

    There is no specific relationship between ORP and FC. Various other factors can influence the ORP reading in ways that have nothing to do with FC levels. You need to adjust the FC to something appropriate and see what your ORP reading is and use that as your ORP target. That process should then be repeated occasionally.

    You need to deal with your CYA and CC levels before you start trying to use ORP control. That pool is in major need of the full shock process (described in Pool School) if that CC reading is even vaguely correct.

    The Taylor CYA test can read levels as high as 20 as if they were zero sometimes. 6 kg in 75,000 gallons would only have raised the CYA level by 21, so you are only just barely at the level where it would be measurable.

    When you do the CYA test, does the sample turn at all cloudy, or does it remain crystal clear?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: ORP Figuring with a CAT 2000 and CYA

    My CYA test sample is still crystal clear.
    Andrew Carlson-Hastings Lake Bible Camp
    Sherwood Park, AB, Canada
    Outdoor IG Pool - 75,500 gal
    Plaster/tile lining - Sand filtered w/two filters
    2 variable speed pumps - Pool constructed in 1973

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