Using the K-2006 CYA test

Exlonghorn

Gold Supporter
Jun 16, 2019
57
Houston
A simple question...when you perform the CYA test using the dual-tube comparator, do you put the comparator in full sun or read it in shade? It makes a 30-40ppm difference in when the black dot “disappears”.
 

jgold723

Member
Jul 5, 2016
14
Biddeford, Maine
Yeah, this test gives me fits, in part because I usually do my testing at night, so I don't have sunlight.

I have a related question: The instructions call for a 30 second agitation of the water/reagent mix before putting the results in the comparison tube -- how precise is that? It seems to me that the cloudiness increases very quickly (when I attempt a second reading of the same mix it almost always comes up higher)
 

taylortechnologies

In The Industry
May 12, 2016
20
Sparks, MD
As with all testing, lighting is critical to obtain the best possible match. We advise that when testing outdoors, have the Sun hit your back or shoulders. Never face the Sun – doing that will alter your test results as the UV light will interfere. The same holds true for the CYA test. Have your back or shoulders to the Sun and not facing it. Remove sunglasses.

CYA wait time: It takes that amount of time, in that size sample bottle (#9191), for the R-0013 to react and combine with the CYA in the sample to produce the correct cloudiness. The precise-ness of the tests is not as high when compared to other methods; however, remember that with CYA you don’t need to be down to one or two decimal places for an answer. I've never experienced the CYA level increasing like you described.
 

Exlonghorn

Gold Supporter
Jun 16, 2019
57
Houston
As with all testing, lighting is critical to obtain the best possible match. We advise that when testing outdoors, have the Sun hit your back or shoulders. Never face the Sun – doing that will alter your test results as the UV light will interfere. The same holds true for the CYA test. Have your back or shoulders to the Sun and not facing it. Remove sunglasses.

CYA wait time: It takes that amount of time, in that size sample bottle (#9191), for the R-0013 to react and combine with the CYA in the sample to produce the correct cloudiness. The precise-ness of the tests is not as high when compared to other methods; however, remember that with CYA you don’t need to be down to one or two decimal places for an answer. I've never experienced the CYA level increasing like you described.
Thanks. In the shade under a patio umbrella late afternoon, the dot appeared to disappear around 70ppm. Reading in full sun at the same time, three feet away (and with the comparator sitting on the edge of the spa being directly lit by afternoon sun) improved contrast and made it easy for me to continue making out the dot with more fluid in the tube....all the way to 40ppm. I'll see if I can post pictures to give a visual on what I'm seeing. Overall, sounds like the lesson is to not let the sun illuminate the comparator directly.