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Thread: Is the OTO test useless if I have high CYA levels?

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    Join Date
    Jun 2014

    Is the OTO test useless if I have high CYA levels?

    CYA is currently in the 80 range. Using the charts here I am targeting FC levels of 9. Does this mean I can't use the OTO daily test as a gauge of levels? Do I now have to use the FAS-DPD test until CYA comes down and FC can be maintained inthe <5 range? I have been using test strips and as long as they are darker than 5 but slightly less than 10 I have been happy so as not to use up the powder quickly.

    Can I "cut" the OTO test with my well tap water and multiply the results by 2? How accurate would I need to be on th half and half fill?
    21k gallon IG vinyl with sand filter and single speed pump. Propane Hayward heater installed with no bypass valves.

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Is the OTO test useless if I have high CYA levels?

    Yes, you're stuck using the FAS-DPD tester. The OTO tester isn't all that exact to start with, and dilution makes it less so.

    You can order refill powder and drops here:
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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  3. Back To Top    #3
    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Is the OTO test useless if I have high CYA levels?

    I mostly agree with Richard here, but will say the OTO test does make for a quick easy sanity check of your ballpark chlorine level
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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