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Thread: CYA Test Method

  1. Back To Top    #1

    Join Date
    Jun 2016

    CYA Test Method

    I first want to thank everyone on this site who helped me embrace the TFP way! I thoroughly enjoyed returning $190 worth of pucks and shock to Sams Club and picking up $30 worth of bleach. You guys helped me turn my swamp into a very nice oasis. Unfortunately, before I found this site I had continued to use the above products trying to clear the water. After reading here and scrambling to get my TF100 kit, I was able to test CYA. I got something well over 100 so I did the dilution method (by 1/2) and got something in the 160 range.

    I noticed some saying that this test is a little tricky to do at first and I have fallen into that demographic. I finally ordered the 50ppm CYA control kit from TFTestKits so I can try and fix my test method with a known CYA value of water.

    I began testing the sample under bright florescent light with the cylinder at my waist and stopped when I didn't see the black dot anymore. The value was 80. I then went outside with the sun at my back and continued again until the black dot went away and the value was 60. I then turned to where the sun was shining through the cylinder and could still see an outline of dot just barely. I added again until it went away and I got something closer to 50 but still not quite.

    So this tells me 1 of 2 things. Either the Control sample they sent is not right (I bet this isn't the case) or I didn't know what I was doing. Apparently you really need to have the sun to do this thing right. I then retested my water to the same method (still using the 1/2 diluted sample) and after doubling got something between 100 and 120. I would call it 110 but I know its definitely not the 160 I thought I had.

    So another couple of partial drains should fix this. In the meantime, I'm keeping my FC between 8 and 12 (about 3/4 a jug a day) so the family can enjoy the sparking pool that you guys helped me to achieve.

    I just wanted to share this to show others that you might need to get the 50CYA Control sample so you can verify your test method. That dot has got to be completely and totally gone. If you think you still see it, you may need to add another couple of drops.
    21K gal, IG Vinyl. Sand Filter (Hayward), Hayward SuperPump 1HP one speed. Pool is at least 25 years old. I inherited the upkeep last year. TF-100 kit, well water-supplied.

  2. Back To Top    #2

    Join Date
    Aug 2015

    Re: CYA Test Method

    I just bought the control sample for the same reason. Found I wasn't as accurate with my lighting as I should be
    ~9600 gal gunite pool, NEW July 2015; Pentair wisperflo 2 spd pump; Pentair C&C 150 filter; Pentair Intelliclor IC40 swg; solar heat w/ Pentair Solartouch controller, screened. Taylor K 2005 test kit, FAS-DPD separate test, Taylor K1766 salt test; Newbie pool owner

  3. Back To Top    #3
    cj3737's Avatar
    Join Date
    Jun 2016
    North Ogden, UT

    Re: CYA Test Method

    ITs actually quite easy with some practice... Bright sunlight with your body shading the sun... I usually put my tester on a rail about waist level and add solution until the dot is faded to a shadow.. then add 1-2 drops at a time until it just disappears. The result may be between 2 marks (lets say it looks like 35) but I will call it 40 to match a target level. Since the test isn't accurate between lines, always aim your FC to the high end of the target.. No control sample needed
    Inherited 24' Muskin Above ground
    13500 gal
    Hayward S180T92S Sand filter
    Taylor K-2006C Speedstir
    TFPC for Beginners | Pool Math | Pool School | CYA Chart | SLAM | Test Kits | ABC's

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