Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 3 of 3

Thread: Retinal fatigue affects appearance of pH test

  1. Back To Top    #1

    Join Date
    Jan 2009
    Cupertino, CA

    Retinal fatigue affects appearance of pH test

    When I use my K-1000 to run OTO and pH tests, a funny thing happens. I close one eye and look through the pH tube; around 7.5. I look at the OTO tube and try to figure out what it says. Then I look back at the pH tube; now it looks more like 7.6 or 7.7. (If I switch eyes then the pH color again matches 7.5.)

    This seems to be an effect of "retinal fatigue" where staring at one color will cause the retina to become desensitized to that color for a while. So, after staring at the OTO tube, part of the retina becomes less sensitive to yellow, then the orange in the pH tube will look more reddish and appear to read higher.

    So be careful when you're doing color matching! Look at the pH tube first, or switch eyes after looking at the yellow OTO tube.
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

  2. Back To Top    #2
    Butterfly's Avatar
    Join Date
    May 2007
    South Carolina

    Re: Retinal fatigue affects appearance of pH test

    Okay, I'm gonna' try this out tomorrow.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  3. Back To Top    #3
    Ohm_Boy's Avatar
    Join Date
    May 2007
    Orlando, FL

    Re: Retinal fatigue affects appearance of pH test

    I've always found that squinting slightly helps when reading these tests.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

Posting Permissions

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