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Thread: OTO or DPD for daily tests?

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    Join Date
    Oct 2015
    Austin, TX

    OTO or DPD for daily tests?

    I have a TFT-100 and within that came a Taylor K-1000 (OTO-based) basic test kit for the daily tests.

    When I ran out of reagents for the K-1000, I tacked one on to an order I had from another pool supply house (as I was already into free shipping) and they sent a K-1001 which is a DPD version of the K-1000.

    Just curious why the TFT-100 has an OTO rather than DPD for the daily tests? Any advantage to using one over the other?


    Pool: 16,000 gallons, 16x31, 500SqFt gunite pool, White Pebbletec interior, built by Cody Pools. Pentair Intelliflo VS-3050 pump, Pentair Clean & Clear 420 Cartridge Filter, In-line chlor with Ultra UV, PV3 Infloor cleaning, Pentair Easytouch-P4 control. TF-100
    Spa: 525 Gallons, Coast fiberglass spa of unknown vintage and suspect previous care with a 2-speed main pump and a blower motor, both 4HP. 3-step bromine sanitized.

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    Mod Squad Texas Splash's Avatar
    Join Date
    Jun 2014
    South-Central Texas, Marion/San Antonio

    Re: OTO or DPD for daily tests?

    Hi Marc. Just to prevent re-inventing the wheel here, you might like THIS THREAD. Might clear it up for you. If not, let us know if you still have questions.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  3. Back To Top    #3
    Mod Squad
    Join Date
    Aug 2012
    DFW, TX

    Re: OTO or DPD for daily tests?

    I use all three. I have the DPD comparator that reads to 10ppm, which is handy since I always maintain more than 5ppm FC. It is a little harder to read the pinks sometimes. And it is pretty easy to calibrate your eye to read the brighter shades of yellow that the OTO test gives you at readings higher than 5 ppm,as Richard says, tweety bird yellow, school bus yellow, etc. I wish they made comparator for OTO that went to 10 ppm. Of course, it would be even better if it went to 11! Maybe I should try my DPD comparator and see how it works.
    TFP Moderator
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    JoyfulNoise's Avatar
    Join Date
    May 2015
    Tucson, AZ

    Re: OTO or DPD for daily tests?

    I prefer the DPD test because it is a true FC test as opposed to OTO which total chlorine.
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: OTO or DPD for daily tests?

    Just curious why the TFT-100 has an OTO rather than DPD for the daily tests?
    The DPD is a poor choice. It only measures to 10 ppm so why not go with the FAS/DPD and get precision at high levels as is as easy as the other.

    The OTO, on the other hand, is included because it is FAST, reliable, and inexpensive. Use it to test for the presence of chlorine, not a precise ppm. Use the FAS/DPD when you want to know the precise number.

    I have users tell me they never use anything but the FAS/DPD because they like the precision. I have other users that know their pools so well they can use the OTO over and over unless they suspect a deviation, then they use the FAS/DPD.

    OTO and FAS/DPD gives you the best of both worlds......DPD gives you neither.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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