Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 8 of 8

Thread: CYA test with Hach DR/850 Colorimeter

  1. Back To Top    #1

    Join Date
    Mar 2007
    Location
    Central PA USA
    Posts
    16

    CYA test with Hach DR/850 Colorimeter

    As everyone knows the CYA test in the Taylor kits leaves a lot to be desired. Recently I found a Hach DR/850 Colorimeter ($20.00 at a public auction --- Local lab went belly up) . I bought the appropriate reagent from Hach ($17.00 for 50 powder pillows) and ran my first test using both methods. I was amazed at the differences in the results.

    I have both the Taylor kit and the Rainbow lifeguard, both showed <20 PPM but the Hach colorimeter result was 35 PPM. I ran a standard using the method in the Hach procedure manual and zeroed the instrument.

    Which result should I believe.

    This instrument is way over kill for the pool but I wonder what other tests (Pool related) it might be good for.
    In-Ground, Vinyl, 27038 Gallons, Fresh Water, CAT 2000 Controller, BBB, Haywood equipment with Perflex DE Filter, Homebrew Solar System (only works when the sun shines);)

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887
    The Hach Colorimeter claims that it can measure CYA from 7 to 55 and is +-1.2 at 25. They don't mention this, but they would obviously be less precise near the ends of the range. The Taylor test measures CYA from 20 to 100 and is +-10 through most of that range, though novice users are often more like +-15 or even +-20 because of difficulty in interpreting the test results. Palintest makes meters that claim a test range for CYA of 0 to 200, though they don't appear to make a precision claim.

    The range on the Hach test is rather narrow. Also, colorimeters typically have trouble with turbidity tests and I find their precision claim difficult to believe. The ColorQ is based on similar technology and it is far less precise than the Taylor test.
    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

  3. Back To Top    #3
    Guest
    The LaMotte waterlink express colorimeter has a range of 0 to 150 ppm with an accuracy of +10/-25 ppm. My experience with this unit is that it consistantly measures low compared to the Taylor test. I tend to beleve the Taylor test.

  4. Back To Top    #4

    Join Date
    Aug 2007
    Location
    Austin, TX
    Posts
    341
    Who makes the most accurate of the Colorimeters on the market?
    20k Gunite/Prism Blue-Pebblesheen, Pentair Tagelus TA-100D Sand Filter, Heliocol Solar Water Heater, 2 bubblers and 2 waterfalls installed 2007, 3hp IntelliFlo VS Pump 011018 installed 2013, Aquabot Turbo T4 RC and Stenner 45MHP10 w/The Liquidator container installed 2012.
    Antigua Spa by Artesian Spas: 325 gl, 52 jets, 6 hp 2 sp & 6 hp 1 sp, Circulation System 24 Hour Whisper Pure, Ozonator, LED digital lighting, The Artesian Pillowfall installed 2007.
    Retired: 2hp Pentair Whisperflow, Legend Platinum w/booster pump, PH Adjuster

  5. Back To Top    #5
    Guest
    Hach and LaMotte both make excellent colorimeters if you want to spend about a thousand dollars or more. Not really sure on Palintest's pricing.

  6. Back To Top    #6

    Join Date
    Mar 2007
    Location
    Central PA USA
    Posts
    16
    Thanks for the input

    The accuracy range of meter is where I like to keep my pool 25-35 so I'll do some further testing to see how it goes.

    None of the pool stores in the area can produce acceptable results and have even detected up to 20 ppm in a sample of distilled water I took them

    I have reagents for 50 tests so.......could be an Ebay item in the future. I'm certain I can get my 20 bucks back.
    In-Ground, Vinyl, 27038 Gallons, Fresh Water, CAT 2000 Controller, BBB, Haywood equipment with Perflex DE Filter, Homebrew Solar System (only works when the sun shines);)

  7. Back To Top    #7

    Join Date
    Apr 2008
    Location
    Austin, Texas
    Posts
    5
    I purchased my Lamote ColorQ Colorimeter for about $250.00. While most test results mirror the Taylor, the
    CYA is way off. Just today Taylor gave me a CYA of 60 while the ColorQ gave me 13.

  8. Back To Top    #8

    Join Date
    Aug 2007
    Location
    Austin, TX
    Posts
    341
    The ColorQ CYA testing on my unit is just as bad as the Pool Store reading. Weekly, I test using the ColorQ vs TF100. Friday's CYA reading on the ColorQ was 6 and TF100 was 40. The week prior I took samples to two differant pool stores and my CYA was about 50 on average. (Both store reading where off...)
    20k Gunite/Prism Blue-Pebblesheen, Pentair Tagelus TA-100D Sand Filter, Heliocol Solar Water Heater, 2 bubblers and 2 waterfalls installed 2007, 3hp IntelliFlo VS Pump 011018 installed 2013, Aquabot Turbo T4 RC and Stenner 45MHP10 w/The Liquidator container installed 2012.
    Antigua Spa by Artesian Spas: 325 gl, 52 jets, 6 hp 2 sp & 6 hp 1 sp, Circulation System 24 Hour Whisper Pure, Ozonator, LED digital lighting, The Artesian Pillowfall installed 2007.
    Retired: 2hp Pentair Whisperflow, Legend Platinum w/booster pump, PH Adjuster

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •